Inefficient Regular Expression Complexity Affecting librechat package, versions <0.8.1-r4


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.02% (6th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-LIBRECHAT-14906011
  • published9 Jan 2026
  • disclosed5 Jan 2026

Introduced: 5 Jan 2026

CVE-2026-0621  (opens in a new tab)
CWE-1333  (opens in a new tab)

How to fix?

Upgrade Chainguard librechat to version 0.8.1-r4 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream librechat package and not the librechat package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

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 Base Scores

version 3.1