Bun npm Scanner

A production-grade security scanner for Bun that integrates with npm registry's GitHub Advisory Database to detect known vulnerabilities in npm packages during installation.

What is GitHub Advisory Database?

The GitHub Advisory Database provides security vulnerability information for open source projects. It is:

• Authoritative: Maintained by GitHub and the open source security community
• Comprehensive: Includes npm Security Advisories and other sources
• Up-to-date: Continuously updated with the latest security advisories
• npm's Official Database: The same database used by bun audit or npm audit

Why Use This Scanner?

Alternative Trust Model: Unlike other scanners that rely on Google's OSV.dev database, this scanner uses npm registry's official vulnerability database powered by GitHub's Advisory Database. This provides:

• Direct from Source: Queries npm registry directly (registry.npmjs.org)
• Microsoft/GitHub Infrastructure: Data sovereignty with Microsoft/GitHub instead of Google
• Official npm Data: Uses the same backend as npm audit and bun audit
• Native Integration: Leverages Bun's built-in gzip compression and performance features

Features

• Real-time Scanning: Checks packages against npm registry during installation
• GitHub Advisory Database: Uses npm's official vulnerability database
• High Performance: Efficient bulk queries with gzip compression
• Fail-safe: Never blocks installations due to scanner errors
• Structured Logging: Configurable logging levels with contextual information
• Precise Matching: Accurate vulnerability-to-package version matching using semver
• Configurable: Environment variable configuration for all settings
• Zero Dependencies: Only uses Bun's built-in features and Zod for validation

Installation

No API keys or registration required - completely free to use with zero setup beyond installation.

# Install as a dev dependency
bun add -d @bun-security-scanner/npm

Configuration

1. Enable the Scanner

Add to your bunfig.toml:

[install.security]
scanner = "@bun-security-scanner/npm"

2. Optional: Configuration Options

The scanner can be configured via environment variables:

# Logging level (debug, info, warn, error)
export NPM_SCANNER_LOG_LEVEL=info

# Custom npm registry URL (optional)
export NPM_SCANNER_REGISTRY_URL=https://registry.npmjs.org

# Request timeout in milliseconds (default: 30000)
export NPM_SCANNER_TIMEOUT_MS=30000

How It Works

Security Scanning Process

1. Package Detection: Bun provides package information during installation
2. Smart Deduplication: Eliminates duplicate package@version queries
3. Bulk Query: Uses npm registry's /npm/v1/security/advisories/bulk endpoint
4. Gzip Compression: Compresses request payload for optimal performance
5. Version Matching: Uses Bun's semver to match vulnerable version ranges
6. Advisory Generation: Creates actionable security advisories

Advisory Levels

The scanner generates two types of security advisories based on npm severity levels:

Fatal (Installation Blocked)

• Severity: critical or high
• Action: Installation is immediately blocked
• Examples: Remote code execution, privilege escalation, data exposure

Warning (User Prompted)

• Severity: moderate, low, or info
• Action: User is prompted to continue or cancel
• TTY: Interactive choice presented
• Non-TTY: Installation automatically cancelled
• Examples: Denial of service, information disclosure, deprecation warnings

Error Handling Philosophy

The scanner follows a fail-safe approach:

• Network errors don't block installations
• Malformed responses are logged but don't halt the process
• Scanner crashes return empty advisory arrays (allows installation)
• Only genuine security threats should prevent package installation

Usage Examples

Basic Usage

# Scanner runs automatically during installation
bun install express
# -> Checks express and all dependencies for vulnerabilities

bun add [email protected]
# -> May warn about known lodash vulnerabilities in older versions

Development Usage

# Enable debug logging to see detailed scanning information
NPM_SCANNER_LOG_LEVEL=debug bun install

# Test with a known vulnerable package
bun add [email protected]
# -> Should trigger security advisory

Configuration Examples

# Increase timeout for slow networks
NPM_SCANNER_TIMEOUT_MS=60000 bun install

# Use custom registry (advanced)
NPM_SCANNER_REGISTRY_URL=https://registry.custom.com bun install

Architecture

The scanner is built with a modular, production-ready architecture:

src/
├── index.ts              # Main scanner implementation
├── client.ts             # npm registry API client with gzip support
├── processor.ts          # Advisory processing and Bun advisory generation
├── cli.ts                # CLI interface for testing
├── schema.ts             # Zod schemas for npm audit API responses
├── constants.ts          # Centralized configuration management
├── logger.ts             # Structured logging with configurable levels
├── retry.ts              # Robust retry logic with exponential backoff
├── severity.ts           # npm severity mapping and assessment
└── types.ts              # TypeScript type definitions

Key Design Principles

1. Separation of Concerns: Each module has a single, well-defined responsibility
2. Error Isolation: Failures in one component don't cascade to others
3. Performance Optimization: Bulk processing, deduplication, and gzip compression
4. Observability: Comprehensive logging for debugging and monitoring
5. Type Safety: Full TypeScript coverage with runtime validation

Comparison with Other Scanners

Testing

# Run the test suite
bun test

# Run with coverage
bun test --coverage

# Type checking
bun run typecheck

# Linting
bun run lint

Development

Building from Source

git clone https://github.com/bun-security-scanner/npm.git
cd npm
bun install
bun run build

Contributing

We do not accept pull requests as this package is actively maintained. However, we appreciate if developers report bugs or suggest features by opening an issue.

API Reference

npm Audit Integration

This scanner integrates with the npm registry bulk advisory endpoint:

• POST /-/npm/v1/security/advisories/bulk: Bulk advisory queries with gzip compression

Request format:

{
  "package-name": ["1.0.0", "2.0.0"],
  "another-package": ["3.0.0"]
}

Response format:

{
  "advisory-id": {
    "id": "GHSA-xxxx-xxxx-xxxx",
    "title": "Vulnerability title",
    "name": "package-name",
    "severity": "high",
    "vulnerable_versions": ">=1.0.0 <2.0.0",
    "url": "https://github.com/advisories/GHSA-xxxx-xxxx-xxxx",
    "overview": "Detailed description..."
  }
}

Configuration Reference

Troubleshooting

Common Issues

Scanner not running during installation?

• Verify bunfig.toml configuration
• Check that the package is installed as a dev dependency
• Enable debug logging: NPM_SCANNER_LOG_LEVEL=debug bun install

Network timeouts?

• Increase timeout: NPM_SCANNER_TIMEOUT_MS=60000
• Check internet connectivity to registry.npmjs.org
• Consider corporate firewall restrictions

Too many false positives?

• npm Advisory Database data is authoritative - verify vulnerabilities manually
• Check if you're using an outdated package version
• Report false positives to GitHub Security Advisories

Debug Mode

Enable comprehensive debug output:

NPM_SCANNER_LOG_LEVEL=debug bun install your-package

This shows:

• Package deduplication statistics
• API request/response details
• Advisory matching decisions
• Performance timing information

License

MIT License - see the LICENSE file for details.

Acknowledgments

• GitHub Advisory Database: For maintaining the comprehensive vulnerability database
• npm Team: For the robust advisory infrastructure
• Bun Team: For the innovative Security Scanner API

Related Projects

• Bun Security Scanner API
• GitHub Advisory Database
• bun-osv-scanner - Alternative scanner using Google's OSV.dev

Last Updated: November 5, 2025 Version: 1.0.0

This scanner provides an alternative trust model for developers who prefer to use npm's official advisory database powered by GitHub.