CVE-2025-49812
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.56%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.4 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.56% probability · 45th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-287
- Affected
- apache/http server
- Source
- security@apache.org
References
- https://httpd.apache.org/security/vulnerabilities_24.htmlVendor Advisory
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.