{"id":"GHSA-8r9q-7v3j-jr4g","revision":"63a6670770814696b7125d3151251807","records":[{"revision":"63a6670770814696b7125d3151251807","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-8r9q-7v3j-jr4g","aliases":["CVE-2026-0621"],"title":"Anthropic's MCP TypeScript SDK has a ReDoS vulnerability","description":"### Impact\n\nA ReDoS vulnerability in the `UriTemplate` class allows attackers to cause denial of service. The `partToRegExp()` function generates a regex pattern with nested quantifiers (`([^/]+(?:,[^/]+)*)`) for exploded template variables (e.g., `{/id*}`, `{?tags*}`), causing catastrophic backtracking on malicious input.\n\n**Who is affected:** MCP servers that register resource templates with exploded array patterns and accept requests from untrusted clients.\n\n**Attack result:** An attacker sends a crafted URI via `resources/read` request, causing 100% CPU utilization, server hang/crash, and denial of service for all clients.\n\n### Affected Versions\n\nAll versions of `@modelcontextprotocol/sdk` prior to the patched release.\n\n### Patches\n\nv1.25.2 contains b392f02ffcf37c088dbd114fedf25026ec3913d3 the fix modifies the regex pattern to prevent backtracking.\n\n### Workarounds\n\n- Avoid using exploded patterns (`{/id*}`, `{?tags*}`) in resource templates\n- Implement request timeouts and rate limiting\n- Validate URIs before processing to reject suspicious patterns","state":0,"publishedAt":"2026-01-05T21:30:33+00:00","modifiedAt":"2026-09-10T03:50:59.009997+00:00","affected":[{"ecosystem":"npm","name":"@modelcontextprotocol/sdk","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"1.3.0"},{"kind":"fixed","version":"1.25.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-cqwc-fm46-7fff","https://nvd.nist.gov/vuln/detail/CVE-2026-0621","https://github.com/modelcontextprotocol/typescript-sdk/issues/965","https://github.com/modelcontextprotocol/typescript-sdk/commit/7f0cf730","https://github.com/modelcontextprotocol/typescript-sdk/commit/b392f02ffcf37c088dbd114fedf25026ec3913d3","https://github.com/modelcontextprotocol/typescript-sdk","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/v1.25.2","https://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redos"],"sourceUrl":"https://github.com/advisories/GHSA-8r9q-7v3j-jr4g","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-8r9q-7v3j-jr4g","identifiers":["GHSA-8r9q-7v3j-jr4g","CVE-2026-0621"]},"retained":false,"historicalAffected":[]}],"coverage":[]}