CVE-2025-49812

Apache HTTP Server: mod_ssl TLS upgrade attack

Published Jul 10, 2025 CVSS 3.1 · 7.4 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4270-1 apache2 security update
EUVD EUVD 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.
Ubuntu USN Ubuntu USN USN-7639-1 Apache HTTP Server vulnerabilities
Ubuntu USN Ubuntu USN USN-7639-2 Apache HTTP Server vulnerabilities
Ubuntu USN Ubuntu USN USN-8338-1 Apache HTTP Server vulnerabilities
History
Type Values Removed Values Added
First Time appeared Apache
Apache http Server
CPEs cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
Vendors & Products Apache
Apache http Server
Type Values Removed Values Added
Metrics epss

{'score': 0.00017}

epss

{'score': 0.00033}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Metrics epss

{'score': 0.00017}

Type Values Removed Values Added
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.
Title Apache HTTP Server: mod_ssl TLS upgrade attack
Weaknesses CWE-287
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apache
Published
Updated
Nov 4, 2025, 9:11 PM
Reserved
Jun 11, 2025, 9:36 AM
Status
Modified
Published
Jul 10, 2025, 5:15 PM
Modified
Jun 17, 2026, 9:31 AM
Severity
Moderate
Public date
Jul 14, 2025, 7:24 AM