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📦
📦 Bitnami
Not in CISA KEV
HIGH severity

CVE-2026-47774 — envoy

HIGH

CVE-2026-47774 is a high-severity (CVSS 7.5) CWE-405 vulnerability in envoy. A fix is available for envoy — see the affected versions and patch details below.

Envoy vulnerable to HTTP/2 memory exhaustion via cookie header size bypass and HPACK amplification

Also known asBIT-envoy-2026-47774GHSA-22m2-hvr2-xqc8
Published
Jun 17, 2026
Updated
Aug 25, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-47774.

EPSS Exploitation Probability

via FIRST.org ↗
1.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-47774 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 381,682 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
📦envoy

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Bitnami packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦Bitnamienvoy≥ 1.36.0&&< 1.35.111.35.11

Affected Products

2 products · 9 configurations
Application
envoyenvoyproxy
≥ 1.37.0 && < 1.37.3
1 version
1.38.0
Application
openshift service meshredhat
≥ 3.3 && < 3.3.4
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for envoy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update envoy to 1.35.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-47774 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant
Workaround published by Red Hat
See the security bulletin for a detailed mitigation procedure.
Source: Red Hat security advisory for CVE-2026-47774 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat OpenShift Service Mesh 2.6openshift-service-mesh/proxyv2-rhel9:1781604724RHSA-2026:27114
Red Hat OpenShift Service Mesh 3.0openshift-service-mesh/istio-proxyv2-rhel9:1781069908RHSA-2026:26210
Red Hat OpenShift Service Mesh 3.1openshift-service-mesh/istio-proxyv2-rhel9:1781070158RHSA-2026:26222
Red Hat OpenShift Service Mesh 3.2openshift-service-mesh/istio-proxyv2-rhel9:1781070967RHSA-2026:26231
Red Hat OpenShift Service Mesh 3.3openshift-service-mesh/istio-proxyv2-rhel9:1781094520RHSA-2026:26247

Frequently Asked Questions

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 e
O3 Security · Impact-Aware SCA

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CVE-2026-47774: envoy — Fixed in 1.35.11 | O3 Security