What’s Vulnerable › Vulnerabilities
CVE-2026-26311: Envoy HTTP: filter chain execution on reset streams causing UAF crash
- Severity: medium (CVSS 5.9 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2026-03-10 · updated 2026-06-17
- Weakness: CWE-416
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 products
- envoyproxy envoy: before 1.34.13; from 1.35.0 before 1.35.8; from 1.36.0 before 1.36.5; 1.37.0 — fixed in 1.34.13, 1.35.8, 1.36.5
How to fix
Upgrade to a fixed version: envoyproxy envoy 1.34.13, 1.35.8, 1.36.5. Check the vendor advisory for mitigations.
References
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