High severity · published Jul 10, 2025
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…
7.4
CVSS
0.6%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 49% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HS
HTTP Server · Apache
before 2.4.64 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-49812
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-49812
Vendor Advisory
https://httpd.apache.org/security/vulnerabilities_24.html
www.openwall.com
http://www.openwall.com/lists/oss-security/2025/07/09/3
www.openwall.com
http://www.openwall.com/lists/oss-security/2025/07/10/2
www.openwall.com
http://www.openwall.com/lists/oss-security/2025/07/10/9
lists.debian.org
https://lists.debian.org/debian-lts-announce/2025/08/msg00009.html
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