CVE-2026-0621
HIGH
GHSA-8r9q-7v3j-jr4g
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
4Description
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.
Analysis
Denial of service in Anthropic MCP TypeScript SDK up to version 1.25.1 stems from catastrophic backtracking in regex processing of RFC 6570 URI templates, allowing remote attackers to trigger excessive CPU consumption and crash Node.js processes without authentication. Public exploit code exists for this vulnerability. …
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Remediation
Within 7 days: Identify all affected systems and apply vendor patches promptly. Monitor vendor channels for patch availability.
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External POC / Exploit Code
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