Envoy: HTTP/2 Discarded Host Header 200 GB Header-Copy OOM in Envoy
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.
CVE-2026-73550
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-73550
envoy
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "envoyproxy",
"product": "envoy",
"versions": [
{
"status": "affected",
"version": "< 1.36.10"
},
{
"status": "affected",
"version": ">= 1.37.0, < 1.37.6"
},
{
"status": "affected",
"version": ">= 1.38.0, < 1.38.4"
},
{
"status": "affected",
"version": ">= 1.39.0, < 1.39.1"
}
]
}
]- Related CVEs
- CVE-2026-73550
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #3340 · Revision 1
- Added to Heist Feed
- Publisher date