VDB
CVE-2026-0621
CVE-2026-0621
PUBLISHED
CVSS 8.699999809265137 HIGH
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.
EPSS 0.05% · 14.7th percentile
Risk Scores
CVSS v4.0
8.699999809265137
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
EPSS Score
0.05%
14.7th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| modelcontextprotocol | sdk | 0 |
| Anthropic | MCP TypeScript SDK | 0 |
| lfprojects | mcp_typescript_sdk | 0 |
Timeline
- Jan 5, 2026 CVE Published
- Jan 5, 2026 PoC Published
- Jan 6, 2026 EPSS Score
- Jan 7, 2026 CVE Updated
- Jan 9, 2026 EPSS Score
- Jan 12, 2026 EPSS Score
- Jan 16, 2026 EPSS Score
- Jan 19, 2026 EPSS Score
- Jan 22, 2026 EPSS Score
- Jan 24, 2026 PoC Published
- Jan 24, 2026 PoC Published
- Jan 25, 2026 EPSS Score
References
- https://github.com/modelcontextprotocol/typescript-sdk/issues/965 issue
- https://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redos third-party-advisory
- https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-cqwc-fm46-7fff url
- https://nvd.nist.gov/vuln/detail/CVE-2026-0621 advisory
- https://github.com/modelcontextprotocol/typescript-sdk/commit/b392f02ffcf37c088dbd114fedf25026ec3913d3 url
- https://github.com/modelcontextprotocol/typescript-sdk package
- https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/v1.25.2 url