CVE-2025-49812: Apache HTTP Server

High severity, CVSS 7.4. EPSS: 0.6% chance of exploitation in the next 30 days.

In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade. Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.

Affected products

• Apache HTTP Server: before 2.4.64 (fixed in 2.4.64)

Published 2025-07-10. Last modified 2026-06-17.