CVE-2025-49812

EUVD-2025-21016
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.4 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA-ADPADP
7.4 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 30%
Affected Products (NVD)
VendorProductVersion
apachehttp_server
𝑥
< 2.4.64
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
apache2
bookworm
2.4.66-1~deb12u1
fixed
bookworm (security)
vulnerable
bullseye
vulnerable
bullseye (security)
2.4.66-1~deb11u1
fixed
forky
2.4.66-8
fixed
sid
2.4.66-8
fixed
trixie
2.4.66-1~deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
apache2
bionic
Fixed 2.4.29-1ubuntu4.27+esm6
released
focal
Fixed 2.4.41-4ubuntu3.23+esm2
released
jammy
Fixed 2.4.52-1ubuntu4.15
released
noble
Fixed 2.4.58-1ubuntu8.7
released
plucky
Fixed 2.4.63-1ubuntu1.1
released
questing
Fixed 2.4.64-1ubuntu1
released
trusty
needs-triage
xenial
Fixed 2.4.18-2ubuntu3.17+esm16
released
Common Weakness Enumeration
References
https://httpd.apache.org/security/vulnerabilities_24.html
http://www.openwall.com/lists/oss-security/2025/07/09/3
http://www.openwall.com/lists/oss-security/2025/07/10/2
http://www.openwall.com/lists/oss-security/2025/07/10/9
https://lists.debian.org/debian-lts-announce/2025/08/msg00009.html