This vulnerability arises from the HTTP handler component of Google mcp-toolbox versions up to and including 1.4.0, which reads incoming request payloads directly into system memory using an unrestricted buffer loop (io.ReadAll) without applying defensive limits such as http.MaxBytesReader or enforcing Content-Length restrictions. This allows an unauthenticated attacker to submit a single, massive HTTP request body that linearly consumes host memory until the runtime process terminates due to an Out-Of-Memory (OOM) error, causing a denial of service condition.

An attacker can cause a denial of service by exhausting system memory through a single large HTTP request to the /mcp endpoint. This results in the termination of the mcp-toolbox process due to an OOM error, disrupting service availability. No authentication or user interaction is required to exploit this vulnerability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider implementing external protections such as limiting request body sizes at network or proxy layers to mitigate potential exploitation.