CVE-2025-3891: Apache HTTP Server

High severity, CVSS 7.5. EPSS: 1.6% chance of exploitation in the next 30 days.

A flaw was found in the mod_auth_openidc module for Apache httpd. This flaw allows a remote, unauthenticated attacker to trigger a denial of service by sending an empty POST request when the OIDCPreservePost directive is enabled. The server crashes consistently, affecting availability.

Affected products

• Apache HTTP Server: affected versions not specified
• Debian Debian Linux: version 11.0 only
• Red Hat Enterprise Linux: version 7.0 only; version 8.0 only; version 9.0 only

Published 2025-04-29. Last modified 2026-06-29.