Reference page — cumulative record through Thursday, October 8, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-73550

CVE-2026-73550HIGH

envoyproxy envoy — Envoy: HTTP/2 Discarded Host Header 200 GB Header-Copy OOM in Envoy

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  N  N  H    7.5   .0055   44.4     —

AFFECTED
  Product  Versions     Fixed
  envoy    < 1.36.10 –  —

TIMELINE
  Aug 12  Reserved by GitHub_M
  Sep 21  Published (CNA: GitHub_M)
  Oct 5   EXPLOIT PUBLISHED — CVE-2026-73550 (envoyproxy envoy). Public exploit reference added.

CWE-401 · CNA: GitHub_M · CVSS v3.1 · 9 references · NVD status: Analyzed

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
August 12, 2026	Reserved	Reserved by GitHub_M
September 21, 2026	Published	Published (CNA: GitHub_M)
October 5, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-73550 (envoyproxy envoy). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
envoyproxy	envoy	—	< 1.36.10	—

Weaknesses

CWE-401

References (9)

https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80 [Patch]
https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2 [Patch]
https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300 [Patch]
https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b [Patch]
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10 [Release Notes]
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6 [Release Notes]
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4 [Release Notes]
https://github.com/envoyproxy/envoy/releases/tag/v1.39.1 [Release Notes]
https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-73550 at cve.org

Vendors: envoyproxy

Weaknesses: CWE-401

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-73550 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Thursday, October 8, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.