CVE-2026-73550High· 7.5▾ TwilightEnvoy 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 pres…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.2 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.9%
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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-73551Medium· 5.3Envoy is an open source edge and service proxy designed for cloud-native applications
CVE-2026-73553High· 7.5Envoy is an open source edge and service proxy designed for cloud-native applications
CVE-2026-73511Medium· 5.3Envoy is an open source edge and service proxy designed for cloud-native applications
CVE-2026-73546High· 7.4Envoy is an open source edge and service proxy designed for cloud-native applications
CVE-2026-73512High· 7.5Envoy is an open source edge and service proxy designed for cloud-native applications
CVE-2026-73548High· 7.5Envoy is an open source edge and service proxy designed for cloud-native applications