| Package | Affected versions | Patched versions |
|---|---|---|
| mcp typescript sdk | ≤ 1.25.1 | |
| @modelcontextprotocol/sdk | ≥ 1.3.0, < 1.25.2 | 1.25.2 |
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.
All versions of @modelcontextprotocol/sdk prior to the patched release.
v1.25.2 contains b392f02ffcf37c088dbd114fedf25026ec3913d3 the fix modifies the regex pattern to prevent backtracking.
{/id*}, {?tags*}) in resource templatesRunning one of these products? Scan your site to see whether it exposes a vulnerable version.
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