CVE-2026-33523: Apache HTTP Server

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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, which fixes the issue.

Affected products

• Apache HTTP Server: from 2.4.0, before 2.4.67 (fixed in 2.4.67)

Published 2026-05-04. Last modified 2026-06-17.