SB20261109230 - Inefficient regular expression complexity in typescript-sdk

CSH
CYBERSECURITY HELP
Sign In REGISTER

Main Vulnerability Database SB20261109230

SB20261109230 - Inefficient regular expression complexity in typescript-sdk

Published: November 9, 2026

Security Bulletin ID SB20261109230
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Inefficient regular expression complexity (CVE-ID: CVE-2026-0621)

CWE-ID: CWE-1333 - Inefficient Regular Expression Complexity

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows an unauthenticated remote attacker to deny service to all clients of affected MCP servers.

The vulnerability exists due to catastrophic regular expression backtracking in the TypeScript SDK's UriTemplate class when matching crafted URIs against registered resource templates with exploded array patterns. An unauthenticated remote attacker can send a crafted URI through a resources/read request to exhaust CPU resources and hang or crash the server.


Remediation

Install update from vendor's website.

References