CVE-2026-0621
CVE-2026-0621 · MCP TypeScript SDK UriTemplate Exploded Array Pattern ReDoS
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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 8.7 · High · EPSS 0.4% · Fix available
- Published
- Updated
Stack: node
Affected products and versions
mcp typescript sdk
- Versions
- ≥ 0, ≤ 1.25.1: Affected (semver)
No fix published
@modelcontextprotocol/sdk npm
- Affected ranges
- SEMVER: ≥ 1.3.0, < 1.25.2
Update to 1.25.2