CVE-2026-73550Envoy: HTTP/2 Discarded Host Header 200 GB Header-Copy OOM in Envoy
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-401
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Sep 28, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
envoyproxy envoy envoyproxy:envoy (from the name) | before 1.36.10; from 1.37.0, < 1.37.6; from 1.38.0, < 1.38.4; from 1.39.0, < 1.39.1 | CNA record |
envoyproxy envoy envoyproxy:envoy | before 1.36.10; from 1.37.0 before 1.37.6; from 1.38.0 before 1.38.4; from 1.39.0 before 1.39.1 | NVD |
References
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvhx-refsource-confirm, exploit, vendor-advisory
- https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80x-refsource-misc, patch
- https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2x-refsource-misc, patch
- https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300x-refsource-misc, patch
- https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61bx-refsource-misc, patch
- https://github.com/envoyproxy/envoy/releases/tag/v1.36.10x-refsource-misc, release-notes
- https://github.com/envoyproxy/envoy/releases/tag/v1.37.6x-refsource-misc, release-notes
- https://github.com/envoyproxy/envoy/releases/tag/v1.38.4x-refsource-misc, release-notes
- https://github.com/envoyproxy/envoy/releases/tag/v1.39.1x-refsource-misc, release-notes
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.