{"cve":"CVE-2026-0621","nvd":{"published":"2026-01-05T21:16:14.533","modified":"2026-10-08T16:16:55.480","status":"Analyzed","description":"Anthropic's MCP TypeScript SDK versions up to and including 1.25.1 contain a regular expression denial of service (ReDoS) vulnerability in the UriTemplate class when processing RFC 6570 exploded array patterns. The dynamically generated regular expression used during URI matching contains nested quantifiers that can trigger catastrophic backtracking on specially crafted inputs, resulting in excessive CPU consumption. An attacker can exploit this by supplying a malicious URI that causes the Node.js process to become unresponsive, leading to a denial of service.","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":8.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-1333"],"references":["https://github.com/modelcontextprotocol/typescript-sdk/issues/965","https://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redos","https://github.com/modelcontextprotocol/typescript-sdk/issues/965"],"products":["lfprojects:mcp_typescript_sdk"],"source":"nvd","synced_at":"2026-10-19T22:19:41.481987139+00:00"},"epss":{"cve":"CVE-2026-0621","score":0.00438,"percentile":0.37815,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-8r9q-7v3j-jr4g","url":"https://osv.dev/vulnerability/GHSA-8r9q-7v3j-jr4g","summary":"Anthropic's MCP TypeScript SDK has a ReDoS vulnerability","modified":"2026-09-10T03:50:59.009997048Z","packages":[{"ecosystem":"npm","name":"@modelcontextprotocol/sdk","purl":"pkg:npm/%40modelcontextprotocol/sdk","ranges":[">=1.3.0 <1.25.2"],"fixed":["1.25.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}