CVE-2025-49812
Apache HTTP Server: mod_ssl TLS upgrade attack
7.4
HIGH
CVSS 3.1
EPSS 0.46%
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.
How to fix CVE-2025-49812
To remediate CVE-2025-49812, upgrade the affected package to a fixed version below.
- —upgrade to 2.4.64-r0 or later
- —upgrade to 2.4.64 or later
- —upgrade to 2.4.65-1~deb11u1 or later
Is CVE-2025-49812 being exploited?
Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 2.4.64-r0
- from 0, < 2.4.64
- from 0, < 2.4.65-1~deb11u1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |