What is CVE-2026-33523?

CVE-2026-33523 is a medium-severity vulnerability in Apache Http_server, classified under CWE-443. CVSS score: 6.5/10. Published 2026-05-04.

How severe is CVE-2026-33523?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Apache Http_server

CVE-2026-33523

HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers. This issue affects Apache HTTP Server: from through 2.4.66. Users are recommended to upgrade to version 2.4.67, w…

EPSS: 0.003 (49.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

Affected products

Apache Http_server
Apache Software Foundation Http Server — versions 2.4.0

Weakness classification (CWE)

CWE-443

References

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

Frequently asked questions

What is CVE-2026-33523?: CVE-2026-33523 is a medium-severity vulnerability in Apache Http_server, classified under CWE-443. CVSS score: 6.5/10. Published 2026-05-04.
How severe is CVE-2026-33523?: Medium severity. CVSS v3 base score is 6.5 out of 10.