Envoy version 1.14.2, 1.13.2, 1.12.4 or earlier is susceptible to increased memory usage in the case where an HTTP/2 client requests a large payload but does not send enough window updates to consume the entire stream and does not reset the stream.
https://github.com/envoyproxy/envoy/security/advisories/GHSA-8hf8-8gvw-ggvx