Evidence · DiggingBeagle record
Advisory: MCP Inspector untrusted tool outputSchema regex freezes UI with exponential validation cost
MCP Inspector validated an MCP server-provided outputSchema.pattern with AJV synchronously in the UI thread. A server could supply a catastrophic-backtracking regular expression and matching-looking structured content. GHSA-2fw8-7jmw-r937 reports rapidly increasing validation time for longer strings and a fix in 2.14.0 (and 1.0.4 on the older branch). The demonstrated effect is client availability degradation, not data theft. Research/disclosure claims are specific to the documented settings; do not infer unreported victims or additional compromise.
- Source role
- primary disclosure
Evidence record
MCP Inspector validated an MCP server-provided outputSchema.pattern with AJV synchronously in the UI thread. A server could supply a catastrophic-backtracking regular expression and matching-looking structured content. GHSA-2fw8-7jmw-r937 reports rapidly increasing validation time for longer strings and a fix in 2.14.0 (and 1.0.4 on the older branch). The demonstrated effect is client availability degradation, not data theft. Research/disclosure claims are specific to the documented settings; do not infer unreported victims or additional compromise.
Claim-level citations (2)
- supportsMCP Inspector validated hostile tool regex schemas on the UI thread: GHSA-2fw8-7jmw-r937 reports rapidly increasing validation time for longer strings and a fix in 2.14.0 (and 1.0.4 on the older branch). The demonstrated effect is client availability degradation, not data theft.
GHSA-2fw8-7jmw-r937; pattern validation timings
- supportsMCP Inspector validated hostile tool regex schemas on the UI thread: MCP Inspector validated an MCP server-provided outputSchema.pattern with AJV synchronously in the UI thread. A server could supply a catastrophic-backtracking regular expression and matching-looking structured content.
GHSA-2fw8-7jmw-r937; pattern validation timings