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CVE-2026-0621

8.7 high SSVC exploitation: poc Analyzed
NVD · CVE.org

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.

Fix

Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.

Change history 1

  1. First seenCVSS 8.7 · lfprojectsNVD modified 2026-10-08 16:16

Affected (CPE criteria) 1

  • cpe:2.3:a:lfprojects:mcp_typescript_sdk:*:*:*:*:*:*:*:*

References 3