Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-06-26T18:01:07 envoy: Envoy: ext_authz Use-After-Free during Stream Teardown with Per-Route Overrides 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H CWE-416

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.36.0 until 1.36.9, 1.37.5, and 1.38.3, a Use-After-Free (UAF) vulnerability leading to a sudden segmentation fault exists in Envoy's ext_authz HTTP filter when processing per-route authorization overrides concurrently with rapid downstream client disconnects. During standard request lifecycles, Envoy instantiates the ext_authz filter with a foundational authorization client object (client_). If a matched route dictates a dynamic per-route HTTP or gRPC authorization service override, the filter generates a localized client. In the vulnerable implementation, this transient client aggressively overwrote the default client_ unique pointer by executing client_ = std::move(per_route_client). When a client rapidly establishes and subsequently tears down a stream (such as rapidly refreshing a protected WebSocket endpoint), the downstream triggers the ConnectionManagerImpl::doDeferredStreamDestroy() -> ActiveStream::onResetStream() lifecycle. Envoy immediately sequences Filter::onDestroy() in an attempt to securely abort dispatched asynchronous authorization check transactions via client_->cancel(). By destructing the default client abruptly during initiateCall, a memory lifecycle misalignment occurs within the async client manager. The stream teardown fails to reliably track and cancel the dynamically bound asynchronous authorization tasks, orchestrating a sequence where a late asynchronous callback from the network evaluates against a heavily destroyed ActiveStream validation span, generating a UAF process crash. This vulnerability is fixed in 1.36.9, 1.37.5, and 1.38.3.

A flaw was found in Envoy's ext_authz HTTP filter. A use-after-free vulnerability exists when processing per-route authorization overrides concurrently with rapid downstream client disconnects. This can lead to a segmentation fault and denial of service.

Red Hat products ship Envoy versions prior to 1.36.0, which do not contain the vulnerable ext_authz per-route override code introduced in 1.36.0. Red Hat products are therefore not affected by this vulnerability. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. OpenShift Service Mesh 2 Not affected openshift-service-mesh/proxyv2-rhel9 OpenShift Service Mesh 3 Not affected openshift-service-mesh/istio-proxyv2-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-47205 https://nvd.nist.gov/vuln/detail/CVE-2026-47205 https://github.com/envoyproxy/envoy/security/advisories/GHSA-mvh9-767w-x47j