CVE-2025-49812

Name	CVE-2025-49812
Description	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.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
apache2 (PTS)	bullseye	2.4.62-1~deb11u1	vulnerable
	bullseye (security)	2.4.62-1~deb11u2	vulnerable
	bookworm, bookworm (security)	2.4.62-1~deb12u2	vulnerable
	trixie	2.4.63-1	vulnerable
	sid	2.4.64-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
apache2	source	(unstable)	2.4.64-1

Notes

https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2025-49812
Fixed by: https://github.com/apache/httpd/commit/87a7351c755c9ef8ab386e3090e44838c2a06d48