CVE-2026-47774: envoyproxy envoy · Asymmetric Resource Consumption
Affects envoyproxy envoySource CVE Database V5
Not known to be exploited · CVSS 7.5 High · fixed in 1.38.1 : patch envoyproxy envoy soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.9% chance of exploitation in 30 days – higher than 61% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-06-17.
- Patch
- Available – fixed in 1.38.1, 1.37.3, 1.36.7 +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 17 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade envoyproxy envoy to 1.38.1, 1.37.3, 1.36.7 or 1.35.11.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| envoyproxyenvoy | Affected
| Fixed in
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| envoyproxyenvoy | Affected
| Fixed in
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| envoyproxyenvoy | Affected
| Fixed in
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| envoyproxyenvoy | Affected
| Fixed in
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Description
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.
References
- github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8 (opens in a new tab)
- openwall.com/lists/oss-security/2026/06/04/15 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-47774 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2487465 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47774.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27114 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26210 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26222 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26231 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26247 (opens in a new tab)