In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26 through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2.

Configurations affected are a reverse proxy is configured for an HTTP/2 backend, with ProxyPreserveHost set to "on".

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4270-1 apache2 security update
EUVD EUVD EUVD-2025-21017 In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26 through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2. Configurations affected are a reverse proxy is configured for an HTTP/2 backend, with ProxyPreserveHost set to "on".
Ubuntu USN Ubuntu USN USN-7639-1 Apache HTTP Server vulnerabilities
Ubuntu USN Ubuntu USN USN-7639-2 Apache HTTP Server vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 04 Nov 2025 22:30:00 +0000


Mon, 03 Nov 2025 20:30:00 +0000

Type Values Removed Values Added
References

Tue, 29 Jul 2025 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Apache http Server
CPEs cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
Vendors & Products Apache http Server

Wed, 16 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00018}

epss

{'score': 0.00052}


Tue, 15 Jul 2025 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 14 Jul 2025 12:15:00 +0000

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


Fri, 11 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00018}


Thu, 10 Jul 2025 17:15:00 +0000

Type Values Removed Values Added
Description In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26 through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2. Configurations affected are a reverse proxy is configured for an HTTP/2 backend, with ProxyPreserveHost set to "on".
Title Apache HTTP Server: mod_proxy_http2 denial of service
Weaknesses CWE-617
References

cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2025-11-04T21:11:13.455Z

Reserved: 2025-06-08T19:44:51.747Z

Link: CVE-2025-49630

cve-icon Vulnrichment

Updated: 2025-11-04T21:11:13.455Z

cve-icon NVD

Status : Modified

Published: 2025-07-10T17:15:48.050

Modified: 2025-11-04T22:16:18.307

Link: CVE-2025-49630

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-07-14T07:22:15Z

Links: CVE-2025-49630 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-07-12T22:44:28Z

Weaknesses