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Tools

4 tools for querying the OSV.dev vulnerability database — single package lookups, batch dependency audits, and full advisory fetch:

Tool	Description
osv_query_package	Query known vulnerabilities for a single package version by name, ecosystem, and version
osv_query_batch	Batch vulnerability query for an array of package tuples — one call for a full dependency list or SBOM audit
osv_get_vulnerability	Fetch the full advisory record for a single OSV vulnerability ID
osv_list_ecosystems	Return the list of supported ecosystem identifier strings

osv_query_package

The primary "is this package version vulnerable?" tool.

• Accepts name, ecosystem (case-sensitive exact match — use osv_list_ecosystems to validate), and version
• Returns all matching advisories: OSV IDs, CVE aliases, CVSS severity vectors, derived severity label, first safe versions, affected version ranges (SEMVER/ECOSYSTEM/GIT), and CWE IDs
• aliases field surfaces CVE IDs for chaining to nist-nvd-mcp-server for CVSS base scores, EPSS exploitation probability, and CISA KEV status
• No API key required — OSV.dev is fully public and keyless

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osv_query_batch

The primary tool for dependency audits, SBOM scanning, and lockfile triage.

• Accepts an array of {name, ecosystem, version} tuples (1–1000 packages per call)
• Ecosystem strings are validated by OSV.dev itself, not a static allowlist — an unrecognized ecosystem surfaces as that entry's per-package error rather than failing the whole batch
• Returns per-package results positionally matching the input, with vulnerable, vulnCount, vulns (including aliases and severityLabel), and fixedVersions
• Includes aggregate summary: totalPackages, vulnerableCount, cleanCount, errorCount, totalVulns, worstSeverity

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osv_get_vulnerability

Fetch the complete advisory record by OSV ID.

• Accepts any OSV ID prefix: GHSA- (GitHub), PYSEC- (Python), RUSTSEC- (Rust), GO- (Go), DSA-/DLA- (Debian), CVE- (direct CVE fallbacks)
• Returns: summary, full advisory details text, all CVE aliases, all affected packages and their version ranges, fix versions, CVSS severity vectors, CWE weakness IDs, and references (ADVISORY, FIX, REPORT, etc.)
• Use after osv_query_package or osv_query_batch returns a vuln ID and you need the full advisory context — remediation guidance, scope of affected packages, or eligibility criteria

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osv_list_ecosystems

Return the list of valid ecosystem identifier strings. Ecosystem strings are case-sensitive exact matches — "pypi" is not "PyPI". Call this tool before querying to validate ecosystem strings from lockfiles or user input. The list is static (sourced from the OSV schema spec) and may occasionally lag newly added ecosystems.

Features

Built on @cyanheads/mcp-ts-core:

• Declarative tool definitions — single file per tool, framework handles registration and validation
• Unified error handling — handlers throw, framework catches, classifies, and formats
• Pluggable auth: none, jwt, oauth
• Swappable storage backends: in-memory, filesystem, Supabase, Cloudflare KV/R2/D1
• Structured logging with optional OpenTelemetry tracing
• STDIO and Streamable HTTP transports

OSV-specific:

• No API key required — OSV.dev is fully public, keyless, and has no published rate limit
• Parallel single-package queries in osv_query_batch return full records including aliases (CVE IDs) that the upstream batch endpoint omits
• Per-package queries isolate failures — one invalid ecosystem or upstream error surfaces as that row's error, leaving the rest of the batch intact

Agent-friendly output:

• aliases (CVE IDs) prominently surfaced on every vuln entry — the primary composition point for chaining to nist-nvd-mcp-server for CVSS base scores, EPSS, and CISA KEV status
• severityLabel derived from database_specific.severity (GHSA records) or the highest CVSS base score; null rather than fabricated when neither source is available
• Echo of query parameters (queryMeta) on osv_query_package output so agents can verify the request was applied correctly
• Batch aggregate summary (worstSeverity, vulnerableCount, cleanCount) for quick triage without reading per-package rows

Getting started

Public Hosted Instance

A public instance is available at https://osv-advisory.caseyjhand.com/mcp — no installation required. Point any MCP client at it via Streamable HTTP:

{
  "mcpServers": {
    "osv-advisory-mcp-server": {
      "type": "streamable-http",
      "url": "https://osv-advisory.caseyjhand.com/mcp"
    }
  }
}

Self-Hosted / Local

Add the following to your MCP client configuration file. No API key is required — OSV.dev is fully public.

{
  "mcpServers": {
    "osv-advisory-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/osv-advisory-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "osv-advisory-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/osv-advisory-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "osv-advisory-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": [
        "run", "-i", "--rm",
        "-e", "MCP_TRANSPORT_TYPE=stdio",
        "ghcr.io/cyanheads/osv-advisory-mcp-server:latest"
      ]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.3.0 or higher (or Node.js v24+).
• No API key required — OSV.dev is fully public.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/osv-advisory-mcp-server.git

2. Navigate into the directory:

cd osv-advisory-mcp-server

3. Install dependencies:

bun install

4. Configure environment:

cp .env.example .env
# edit .env if needed (no required vars)

Configuration

All configuration is validated at startup. No server-specific env vars are required — OSV.dev is keyless and fully public.

Variable	Description	Default
OSV_REQUEST_TIMEOUT_MS	HTTP request timeout in milliseconds for OSV.dev API calls.	10000
MCP_TRANSPORT_TYPE	Transport: stdio or http.	stdio
MCP_HTTP_PORT	Port for HTTP server.	3010
MCP_HTTP_ENDPOINT_PATH	HTTP endpoint path.	/mcp
MCP_PUBLIC_URL	Public origin override for TLS-terminating reverse-proxy deployments.	none
MCP_AUTH_MODE	Auth mode: none, jwt, or oauth.	none
MCP_LOG_LEVEL	Log level (RFC 5424).	info
LOGS_DIR	Directory for log files (Node.js only).	<project-root>/logs
STORAGE_PROVIDER_TYPE	Storage backend.	in-memory
OTEL_ENABLED	Enable OpenTelemetry instrumentation (spans, metrics, completion logs).	false

See .env.example for the full list of optional overrides.

Running the server

Local development

• Build and run:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http
  

• Run checks and tests:

  bun run devcheck   # Lint, format, typecheck, security
  bun run test       # Vitest test suite
  bun run lint:mcp   # Validate MCP definitions against spec
  

Docker

docker build -t osv-advisory-mcp-server .
docker run --rm -p 3010:3010 osv-advisory-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/osv-advisory-mcp-server. OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Directory	Purpose
src/index.ts	createApp() entry point — registers tools and inits services.
src/mcp-server/tools	Tool definitions (*.tool.ts) — osv_query_package, osv_query_batch, osv_get_vulnerability, osv_list_ecosystems.
src/services/osv-api	OSV.dev REST API service — fetch, retry, response normalization.
tests/	Unit and integration tests mirroring src/.

Development guide

See CLAUDE.md/AGENTS.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic
• Use ctx.log for request-scoped logging, ctx.state for tenant-scoped storage
• Register new tools via the barrel in src/mcp-server/tools/definitions/index.ts
• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Contributing

Issues and pull requests are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.