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Vulnerability · Published Mar 10, 2026 · Assigned by GitHub_M

CVE-2026-26311Envoy HTTP: filter chain execution on reset streams causing UAF crash

Medium 5.9

In plain English

A medium-severity use-after-free in envoy from envoyproxy. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities).

Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.4%top 66.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, a logic vulnerability in Envoy's HTTP connection manager (FilterManager) that allows for Zombie Stream Filter Execution. This issue creates a "Use-After-Free" (UAF) or state-corruption window where filter callbacks are invoked on an HTTP stream that has already been logically reset and cleaned up. The vulnerability resides in source/common/http/filter_manager.cc within the FilterManager::decodeData method. The ActiveStream object remains valid in memory during the deferred deletion window. If a DATA frame arrives on this stream immediately after the reset (e.g., in the same packet processing cycle), the HTTP/2 codec invokes ActiveStream::decodeData, which cascades to FilterManager::decodeData. FilterManager::decodeData fails to check the saw_downstream_reset_ flag. It iterates over the decoder_filters_ list and invokes decodeData() on filters that have already received onDestroy(). This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/envoyproxy/envoyno fix listedGHSA-84xm-r438-86px
Gogithub.com/envoyproxy/envoyno fix listedGHSA-84xm-r438-86px
Gogithub.com/envoyproxy/envoyno fix listedGHSA-84xm-r438-86px
Gogithub.com/envoyproxy/envoyno fix listedGHSA-84xm-r438-86px

Affected products (as reported)

VendorProductVersions
envoyproxy envoy >= 1.37.0, < 1.37.1>= 1.36.0, < 1.36.5>= 1.35.0, < 1.35.9< 1.34.13

Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References