Envoy is a cloud-native high-performance edge/middle/service proxy. Envoy’s HTTP/2 codec may leak a header map and bookkeeping structures upon receiving RSTSTREAM immediately followed by the GOAWAY frames from an upstream server. In nghttp2, cleanup of pending requests due to receipt of the GOAWAY frame skips de-allocation of the bookkeeping structure and pending compressed header. The error return [code path] is taken if connection is already marked for not sending more requests due to GOAWAY frame. The clean-up code is right after the return statement, causing memory leak. Denial of service through memory exhaustion. This vulnerability was patched in versions(s) 1.26.3, 1.25.8, 1.24.9, 1.23.11.