Vulnerability 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 Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Apache | Http Server | < 2.4.64 |
Related Weaknesses (CWE)
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
FAQ
What is CVE-2025-49812?
CVE-2025-49812 is a vulnerability with a CVSS score of 7.4 (HIGH). 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...
How severe is CVE-2025-49812?
CVE-2025-49812 has been rated HIGH with a CVSS base score of 7.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-49812?
Check the references section above for vendor advisories and patch information. Affected products include: Apache Http Server.