CVE-2026-0621

7.5 HIGH
Published: January 05, 2026 Modified: January 30, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/modelcontextprotocol/typescript-sdk/issues/965
Source: disclosure@vulncheck.com
Exploit Issue Tracking
https://github.com/modelcontextprotocol/typescript-sdk/issues/965
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Issue Tracking

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
7.5 / 10.0
EPSS (Exploit Probability)
0.0%
6th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

lfprojects