Disclosure summary
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.
Source-reported weakness categories
CWE-1333
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2026-0621
Open original source · Updated Oct 08, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
| Vendor | Product / association | Version / bounds |
|---|---|---|
| lfprojects | mcp_typescript_sdk | * {"versionEndIncluding":"1.25.1"} |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Exploit, Issue Tracking
- www.vulncheck.com — Third Party Advisory
- github.com — Exploit, Issue Tracking
PUBLISHED 2026-01-05T16:16:14-05:00
MODIFIED 2026-10-08T12:16:55-04:00
INGESTED 2026-10-10T20:50:35-04:00