What is CVE-2026-34356?

CVE-2026-34356 is a high-severity vulnerability in Apache Http_server, classified under Heap-based Buffer Overflow. CVSS score: 7.5/10. Published 2026-06-08.

How severe is CVE-2026-34356?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Apache Http_server

CVE-2026-34356

Heap-based Buffer Overflow vulnerability in Apache HTTP Server with malicious backend servers and ProxyPassReverseCookie* This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.6…

Vulnerability class: Buffer Overflow

EPSS: 0.007 (48.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Apache Http_server
Apache Software Foundation Http Server — versions 2.4.0

Weakness classification (CWE)

CWE-122 — Heap-based Buffer Overflow

References

security@apache.org (vendor-advisory, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List)

Frequently asked questions

What is CVE-2026-34356?: CVE-2026-34356 is a high-severity vulnerability in Apache Http_server, classified under Heap-based Buffer Overflow. CVSS score: 7.5/10. Published 2026-06-08.
How severe is CVE-2026-34356?: High severity. CVSS v3 base score is 7.5 out of 10.