Detections
Analytics
CVE-2026-73550
high
Description
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy copies every decoded HTTP/2 Host header value before discarding it when :authority is already present. The discarded value bypasses saveHeader, so its bytes and count are not charged against request header limits. An unauthenticated client can use HPACK indexing to submit many references to a large Host value across a bounded number of streams, forcing extreme header-copy allocation and causing the proxy to be out-of-memory killed. The relevant scope boundary is that the demonstrated amplification uses HTTP/2 HPACK and the duplicate Host discard behavior. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.
References
https://docs.cloud.google.com/support/bulletins/index#gcp-2026-057
https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh
https://github.com/envoyproxy/envoy/releases/tag/v1.39.1
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10
https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b
https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300
https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2
https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80