CVE-2026-47205: Envoy Use-After-Free in ext_authz filter during stream teardown

CVE-2026-47205 · Severity: medium · CVSS 5.9 · Published 2026-06-26

Envoy, a widely used service proxy for cloud-native applications, is vulnerable to a flaw in its external authorization component. An attacker can cause the proxy to crash by rapidly opening and closing connections to specific routes that use custom authorization settings. This results in a denial-of-service (DoS) condition, potentially disrupting all traffic and services managed by the affected proxy.

Technologies: Envoy Proxy Envoy. Vendors: Envoy Proxy.

Quick answers

Is CVE-2026-47205 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-47205 being exploited in the wild.
How severe is CVE-2026-47205?
Medium severity, with a CVSS score of 5.9, published 26 June 2026.
Which products and versions are affected?
Envoy Proxy Envoy 1.36.0 to 1.36.8, 1.37.0 to 1.37.4, 1.38.0 to 1.38.2.
Is there a fix for CVE-2026-47205?
A patch was published on 2026-06-26: Fixes released in versions 1.36.9, 1.37.5, and 1.38.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-47205 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-47205?
Check whether you run Envoy Proxy Envoy 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 Use-After-Free (UAF) vulnerability exists in the Envoy ext_authz HTTP filter due to improper memory management of authorization client objects. When a route uses a dynamic per-route HTTP or gRPC authorization override, the filter overwrites its default client pointer with a transient one. If a downstream client disconnects rapidly (e.g., during a WebSocket handshake), the filter attempts to cancel the asynchronous authorization task using a pointer that has already been destroyed or misaligned. This race condition triggers a segmentation fault and process crash. The vulnerability affects versions 1.36.x, 1.37.x, and 1.38.x and is fixed in versions 1.36.9, 1.37.5, and 1.38.3.

Affected products

  • Envoy Proxy Envoy 1.36.0 to 1.36.8, 1.37.0 to 1.37.4, 1.38.0 to 1.38.2

Timeline

  • 2026-06-23: advisory: GitHub Security Advisory published by maintainers
  • 2026-06-26: disclosed: NVD publication date
  • 2026-06-26: patched: Fixes released in versions 1.36.9, 1.37.5, and 1.38.3

References

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