CVE-2026-47774
What it is
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability in Envoy's HTTP/2 downstream request processing allows an unauthenticated remote client to trigger excessive memory consumption, potentially resulting in OOM termination of the Envoy process and denial of service. The issue arises from the combination of two behaviors. First, cookie header bytes are not fully accounted for during request header size validation in Envoy. Second, HPACK header block limits in oghttp2/quiche are enforced on encoded bytes without a corresponding limit on total decoded header size. Together, these behaviors allow a malicious client to cause large decoded header allocations while bypassing the intended request header size protections. Versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 contain a fix. No complete workaround is known short of applying a fix. Possible temporary mitigations include disabling downstream HTTP/2 where operationally feasible; enforcing stricter request header and cookie limits before traffic reaches Envoy; and monitoring Envoy memory usage for abnormal growth under HTTP/2 traffic.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 1.0% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.0% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.0% · EPSS, next 30 days
- Weakness
- CWE-405
- Record status
- Analyzed
Affected
- Envoyproxy Envoy < 1.35.11
- Envoyproxy Envoy < 1.36.7
- Envoyproxy Envoy < 1.37.3
- Envoyproxy Envoy 1.38.0
- Redhat Openshift Service Mesh < 2.6.17
- Redhat Openshift Service Mesh < 3.0.12
- Redhat Openshift Service Mesh < 3.1.9
- Redhat Openshift Service Mesh < 3.2.6
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-47774.md and follow it. Check whether this project is affected by CVE-2026-47774. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8
- http://www.openwall.com/lists/oss-security/2026/06/04/15
References
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8
- http://www.openwall.com/lists/oss-security/2026/06/04/15
- https://access.redhat.com/errata/RHSA-2026:26210
- https://access.redhat.com/errata/RHSA-2026:26222
- https://access.redhat.com/errata/RHSA-2026:26231
- https://access.redhat.com/errata/RHSA-2026:26247
- https://access.redhat.com/errata/RHSA-2026:27114
- https://access.redhat.com/security/cve/CVE-2026-47774
- https://bugzilla.redhat.com/show_bug.cgi?id=2487465
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47774.json