CVE-2026-0621: Anthropic's MCP TypeScript SDK versions up to and including 1.25.1 contain a regular expression denial of service (ReDoS…
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.
- Published by source
- 2026-01-05
- First seen by Reality Radar
- 2026-10-27
- Last verified
- 2026-10-27
Affected
- Manufacturer
- lfprojects
- Products
- mcp typescript sdk
- Versions
- <=1.25.1
- CPE
- cpe:2.3:a:lfprojects:mcp_typescript_sdk:*:*:*:*:*:*:*:*
Whether your exact unit is affected depends on the model, serial number and region in the official notice.
What the official notice says
Risk: CVSS 8.7
Is this affecting you?
Add what you own or use and Reality Radar will tell you when official changes match it — with evidence and next steps.
Sources
- NIST National Vulnerability Database Tier A · official published 2026-01-05
Evidence ledger
Every piece of evidence we store is appended to a public hash chain, so later edits are detectable. Anyone can re-verify it.
| Entry | Kind | Observed | Evidence hash | Entry hash |
|---|---|---|---|---|
| #2130 | new | 2026-10-27 | c23ac937ae1a…acaefa | 933ba4e7b82b…6c8991 |
Chain head: #2286 e212558e872c…954bc1