What is CVE-2026-26311?

CVE-2026-26311 is a medium-severity vulnerability in Envoyproxy Envoy, classified under Use After Free. CVSS score: 5.9/10. Published 2026-03-10.

How severe is CVE-2026-26311?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Use After Free in Envoyproxy Envoy

CVE-2026-26311

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 create…

Vulnerability class: Use-After-Free

EPSS: 0.000 (5.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Envoyproxy Envoy — versions >= 1.37.0, < 1.37.1, >= 1.36.0, < 1.36.5, >= 1.35.0, < 1.35.9

Weakness classification (CWE)

CWE-416 — Use After Free

References

https://github.com/envoyproxy/envoy/security/advisories/GHSA-84xm-r438-86px (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-26311?: CVE-2026-26311 is a medium-severity vulnerability in Envoyproxy Envoy, classified under Use After Free. CVSS score: 5.9/10. Published 2026-03-10.
How severe is CVE-2026-26311?: Medium severity. CVSS v3 base score is 5.9 out of 10.