Anthropic's MCP TypeScript SDK has a ReDoS vulnerability
Exact source revision recorded 24 Oct 2026 13:17:17 UTC. It does not establish the source's current position. Latest evidence.
osv · GHSA-8r9q-7v3j-jr4g
Published### Impact A ReDoS vulnerability in the `UriTemplate` class allows attackers to cause denial of service. The `partToRegExp()` function generates a regex pattern with nested quantifiers (`([^/]+(?:,[^/]+)*)`) for exploded template variables (e.g., `{/id*}`, `{?tags*}`), causing catastrophic backtracking on malicious input. **Who is affected:** MCP servers that register resource templates with exploded array patterns and accept requests from untrusted clients. **Attack result:** An attacker sends a crafted URI via `resources/read` request, causing 100% CPU utilization, server hang/crash, and denial of service for all clients. ### Affected Versions All versions of `@modelcontextprotocol/sdk` prior to the patched release. ### Patches v1.25.2 contains b392f02ffcf37c088dbd114fedf25026ec3913d3 the fix modifies the regex pattern to prevent backtracking. ### Workarounds - Avoid using exploded patterns (`{/id*}`, `{?tags*}`) in resource templates - Implement request timeouts and rate limiting - Validate URIs before processing to reject suspicious patterns
- Source published
- 5 Jan 2026 21:30:33 UTC
- Source modified
- 10 Sep 2026 03:50:59 UTC
- Observed here
- 24 Oct 2026 13:17:17 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS_V4 · 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
Publisher rating · HIGH