CVE-2026-47774: Envoy Proxy denial of service via HTTP/2 HPACK amplification

CVE-2026-47774 · Severity: high · CVSS 7.5 · Published 2026-06-17

Envoy is a widely used open-source proxy that manages network traffic for cloud applications. A vulnerability in how it handles certain web requests allows an attacker to force the system to consume massive amounts of memory very quickly. This can cause the service to crash, leading to a total outage for the applications it protects.

Technologies: Envoy Proxy Envoy, Google Cloud Platform. Vendors: Envoy Proxy, Google.

Quick answers

Is CVE-2026-47774 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-47774 being exploited in the wild.
How severe is CVE-2026-47774?
High severity, with a CVSS score of 7.5, published 17 June 2026.
Which products and versions are affected?
Envoy Proxy Envoy < 1.35.11, >= 1.36.0 < 1.36.7, >= 1.37.0 < 1.37.3, >= 1.38.0 < 1.38.1.
Is there a fix for CVE-2026-47774?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-47774 attacked?
It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-47774?
Check whether you run Envoy Proxy Envoy or Google Cloud Platform at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in Envoy's HTTP/2 downstream request processing due to a combination of two flaws: incomplete accounting of cookie header bytes during request header size validation and the enforcement of HPACK header block limits on encoded bytes rather than decoded size in the oghttp2/quiche component. An unauthenticated remote attacker can exploit this by sending specially crafted cookie headers using HPACK dynamic table references to cause large memory allocations while bypassing 'max_request_headers_kb' protections. This can be further amplified by HTTP/2 flow-control stalling to delay memory reclamation, leading to Out-Of-Memory (OOM) termination. Patches are available in versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1.

Affected products

  • Envoy Proxy Envoy < 1.35.11, >= 1.36.0 < 1.36.7, >= 1.37.0 < 1.37.3, >= 1.38.0 < 1.38.1

Timeline

  • 2026-06-03: advisory: GitHub advisory GHSA-22m2-hvr2-xqc8 published
  • 2026-06-17: disclosed: CVE-2026-47774 published to NVD

References

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