CVE-2026-0621

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 v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

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

Configurations

Configuration 1 (hide)

cpe:2.3:a:lfprojects:mcp_typescript_sdk:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-01-05 21:16

Updated : 2026-01-30 01:16

NVD link : CVE-2026-0621

Mitre link : CVE-2026-0621

CVE.ORG link : CVE-2026-0621

JSON object : View

Products Affected

lfprojects

mcp_typescript_sdk

CWE

CWE-1333

Inefficient Regular Expression Complexity

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