CVE-2026-0621

HIGH EPSS 31.8%
Published Jan 5, 20265mo ago · Modified Jun 17, 20261w ago
8.7 CVSS 4.0
High
Find Similar
Published Jan 5, 2026 5mo ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
8.7
Exploitability
—
Impact
—
Vector string
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
31.8% percentile
Exploit & Patch Status
Public Exploit Known
No Patch Available

Weaknesses 1

CWE-1333

Affected Products 1

VendorProductVersionRange
lfprojectsmcp_typescript_sdk* ≤1.25.1

References 2

  • github.com https://github.com/modelcontextprotocol/typescript-sdk/issues/965
    ExploitIssue Tracking
  • vulncheck.com https://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redos
    Third Party Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.