Bun OSV Scanner

A production-grade security scanner for Bun that integrates with OSV.dev (Open Source Vulnerabilities) to detect known vulnerabilities in npm packages during installation.

What is OSV.dev?

OSV.dev is Google's open source vulnerability database that aggregates and distributes vulnerability information for open source projects. It provides:

• Comprehensive Coverage: Vulnerabilities from multiple sources (npm, PyPI, Go, Rust, etc.)
• Structured Data: Machine-readable vulnerability information with precise version ranges
• Real-time Updates: Continuously updated with the latest security advisories
• Authoritative Source: Maintained by Google and the open source community

Features

• Real-time Scanning: Checks packages against OSV.dev during installation
• High Performance: Efficient batch queries with smart deduplication
• 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
• Configurable: Environment variable configuration for all settings
• Well Tested: Comprehensive test suite with edge case coverage

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/osv

Configuration

1. Enable the Scanner

Add to your bunfig.toml:

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

2. Optional: Configuration Options

The scanner can be configured via environment variables:

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

# Custom OSV API base URL (optional)
export OSV_API_BASE_URL=https://api.osv.dev/v1

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

# Disable batch queries (default: false)
export OSV_DISABLE_BATCH=false

How It Works

Security Scanning Process

1. Package Detection: Bun provides package information during installation
2. Smart Deduplication: Eliminates duplicate package@version queries
3. Batch Querying: Uses OSV.dev's efficient /querybatch endpoint
4. Vulnerability Matching: Precisely matches vulnerabilities to installed versions
5. Severity Assessment: Analyzes CVSS scores and database-specific severity
6. Advisory Generation: Creates actionable security advisories

Advisory Levels

The scanner generates two types of security advisories:

Fatal (Installation Blocked)

• CVSS Score: ≥ 7.0 (High/Critical)
• Database Severity: CRITICAL or HIGH
• Action: Installation is immediately blocked
• Examples: Remote code execution, privilege escalation, data exposure

Warning (User Prompted)

• CVSS Score: < 7.0 (Medium/Low)
• Database Severity: MEDIUM, LOW, or unspecified
• 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
OSV_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
OSV_TIMEOUT_MS=60000 bun install

# Use custom OSV instance (advanced)
OSV_API_BASE_URL=https://api.custom-osv.dev/v1 bun install

Architecture

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

src/
├── index.ts              # Main scanner implementation
├── client.ts             # OSV.dev API client with batch support
├── processor.ts          # Vulnerability processing and advisory generation
├── cli.ts                # CLI interface for testing
├── schema.ts             # Zod schemas for OSV API responses
├── constants.ts          # Centralized configuration management
├── logger.ts             # Structured logging with configurable levels
├── retry.ts              # Robust retry logic with exponential backoff
├── semver.ts             # OSV semver range matching
├── severity.ts           # CVSS and severity 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: Batch processing, deduplication, and concurrent requests
4. Observability: Comprehensive logging for debugging and monitoring
5. Type Safety: Full TypeScript coverage with runtime validation

Testing

# Run the test suite
bun test

# Run with coverage
bun test --coverage

# Type checking
bun run typecheck

# Linting
bun run lint

Test Coverage

• Known vulnerable packages detection
• Safe package verification
• Multiple package scenarios
• Version-specific vulnerability matching
• Network failure handling
• Edge cases and error conditions

Development

Building from Source

git clone https://github.com/bun-security-scanner/osv.git
cd osv
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.

See CONTRIBUTING.md for more details.

API Reference

OSV.dev Integration

This scanner integrates with the following OSV.dev endpoints:

• POST /v1/querybatch: Batch vulnerability queries for multiple packages
• POST /v1/query: Individual package queries with pagination support

For complete OSV.dev API documentation, visit: https://google.github.io/osv.dev/api/

Configuration Reference

| Environment Variable | Default | Description | |---------------------|---------|-------------| | OSV_LOG_LEVEL | info | Logging level: debug, info, warn, error | | OSV_API_BASE_URL | https://api.osv.dev/v1 | OSV API base URL | | OSV_TIMEOUT_MS | 30000 | Request timeout in milliseconds | | OSV_DISABLE_BATCH | false | Disable batch queries (use individual queries) |

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: OSV_LOG_LEVEL=debug bun install

Network timeouts?

• Increase timeout: OSV_TIMEOUT_MS=60000
• Check internet connectivity to osv.dev
• Consider corporate firewall restrictions

Too many false positives?

• OSV.dev data is authoritative - verify vulnerabilities manually
• Check if you're using an outdated package version
• Report false positives to the OSV.dev project

Debug Mode

Enable comprehensive debug output:

OSV_LOG_LEVEL=debug bun install your-package

This shows:

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

License

MIT License - see the LICENSE file for details.

Acknowledgments

• OSV.dev Team: For maintaining the comprehensive vulnerability database
• Bun Team: For the innovative Security Scanner API

Related Projects

• Bun Security Scanner API
• OSV.dev - Open Source Vulnerabilities database

Last Updated: November 6, 2025 Version: 1.0.0

This documentation is a living document and will be updated as the project evolves and new features are added.