Integer overflow in Apache HTTP Server - CVE-2025-55753

Vulnerability identifier: #VU119150

CSH Severity: Low

CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2025-55753

CWE-ID: CWE-190

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform a denial of service attack.

The vulnerability exists due to an integer overflow in mod_md (ACME) in the case of failed ACME certificate renewal. The web server will set the backoff timer becoming 0 after a number of failures (~30 days in default configurations), leading to a denial of service condition.

Apache HTTP Server
Gentoo Linux
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Manager Proxy 4.3
SUSE Manager Retail Branch Server 4.3
SUSE Manager Server 4.3
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Manager Server
SUSE Manager Retail Branch Server
SUSE Manager Proxy
Anolis OS
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux Server - TUS
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
macOS
Ubuntu
Basesystem Module
Server Applications Module
SUSE Package Hub 15
openSUSE Leap
openEuler
Oracle Solaris
IBM Cloud Pak System
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
mod_http2
mod_md
md (Red Hat package)
apache2 (Ubuntu package)
mod_md (Red Hat package)
httpd-filesystem
httpd-tools
httpd-devel
mod_ldap
httpd
mod_proxy_html
mod_session
mod_ssl
httpd-manual
httpd-help
httpd-debuginfo
httpd-debugsource
apache2-prefork-debuginfo
apache2-tls13-worker-debuginfo
apache2-worker
apache2-utils-debuginfo
apache2-tls13-worker
apache2-tls13-example-pages
apache2-debugsource
apache2-debuginfo
apache2-prefork
apache2-worker-debuginfo
apache2-tls13-devel
apache2-tls13-debugsource
apache2
apache2-utils
apache2-tls13-doc
apache2-doc
apache2-example-pages
apache2-tls13-debuginfo
apache2-tls13-prefork
apache2-devel
apache2-tls13-utils
apache2-tls13-utils-debuginfo
apache2-tls13
apache2-tls13-prefork-debuginfo
apache2-event-debuginfo
apache2-event
apache2-manual
apache2-worker-debugsource
apache2-prefork-debugsource
apache2-utils-debugsource
apache2-event-debugsource
mod_lua
httpd-core
httpd-doc
www-servers/apache
IBM Cloud Object Storage Systems

Install updates from vendor's website.

Apache HTTP Server - update to 2.4.66
IBM Cloud Pak System - update to 2.3.5.1
macOS - addressed in versions 14.8.5 23J423, 15.7.5 24G624, 26.4 25E246
mod_http2 - update to 1.15.7-10
mod_md - update to 2.0.8-8
md (Red Hat package) - addressed in versions 2.4.0-3.el9_0.1, 2.4.19-1.el9_2.1, 2.4.19-1.el9_4.1, 2.4.26-1.el9_7.1, 2.4.26-3.el10_0.1
apache2 (Ubuntu package) - addressed in versions 2.4.7-1ubuntu4.22+esm12, 2.4.18-2ubuntu3.17+esm17, 2.4.29-1ubuntu4.27+esm7, 2.4.29-1ubuntu4.27+esm8, 2.4.41-4ubuntu3.23+esm3, 2.4.52-1ubuntu4.18, 2.4.52-1ubuntu4.19, 2.4.58-1ubuntu8.10, 2.4.58-1ubuntu8.11, 2.4.64-1ubuntu3.2, 2.4.64-1ubuntu3.3
mod_md (Red Hat package) - update to 2.4.26-4.el10_1
httpd-filesystem - addressed in versions 2.4.37-655.0.1, 2.4.66-1
httpd-tools - addressed in versions 2.4.37-655.0.1, 2.4.66-1
httpd-devel - addressed in versions 2.4.37-655.0.1, 2.4.66-1
mod_ldap - addressed in versions 2.4.37-655.0.1, 2.4.66-1
httpd - addressed in versions 2.4.37-655.0.1, 2.4.66-1
mod_proxy_html - addressed in versions 2.4.37-655.0.1, 2.4.66-1
mod_session - addressed in versions 2.4.37-655.0.1, 2.4.66-1
mod_ssl - addressed in versions 2.4.37-655.0.1, 2.4.66-1
httpd-manual - addressed in versions 2.4.37-655.0.1, 2.4.66-1
mod_session - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd-help - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd-filesystem - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
mod_ssl - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd-debuginfo - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd-debugsource - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd-devel - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
httpd-tools - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
mod_ldap - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
mod_md - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
mod_proxy_html - addressed in versions 2.4.43-32, 2.4.51-27, 2.4.58-12
apache2-prefork-debuginfo - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-tls13-worker-debuginfo - update to 2.4.51-35.75.1
apache2-worker - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-utils-debuginfo - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-tls13-worker - update to 2.4.51-35.75.1
apache2-tls13-example-pages - update to 2.4.51-35.75.1
apache2-debugsource - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-debuginfo - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-prefork - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-worker-debuginfo - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-tls13-devel - update to 2.4.51-35.75.1
apache2-tls13-debugsource - update to 2.4.51-35.75.1
apache2 - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-utils - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-tls13-doc - update to 2.4.51-35.75.1
apache2-doc - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.66-150400.6.57.1
apache2-example-pages - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.66-150400.6.57.1
apache2-tls13-debuginfo - update to 2.4.51-35.75.1
apache2-tls13-prefork - update to 2.4.51-35.75.1
apache2-devel - addressed in versions 2.4.51-35.75.1, 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-tls13-utils - update to 2.4.51-35.75.1
apache2-tls13-utils-debuginfo - update to 2.4.51-35.75.1
apache2-tls13 - update to 2.4.51-35.75.1
apache2-tls13-prefork-debuginfo - update to 2.4.51-35.75.1
apache2-event-debuginfo - addressed in versions 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-event - addressed in versions 2.4.51-150400.6.52.1, 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1, 2.4.66-150400.6.57.1
apache2-manual - update to 2.4.58-150600.5.41.1
apache2-worker-debugsource - addressed in versions 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1
apache2-prefork-debugsource - addressed in versions 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1
apache2-utils-debugsource - addressed in versions 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1
apache2-event-debugsource - addressed in versions 2.4.58-150600.5.41.1, 2.4.62-150700.4.9.1
mod_lua - update to 2.4.66-1
httpd-core - update to 2.4.66-1
httpd-doc - update to 2.4.66-1
www-servers/apache - update to 2.4.68
IBM Cloud Object Storage Systems - addressed in versions 3.20.0.43, 3.20.0.69
Oracle Solaris - addressed in versions 11.3 ESU 36.35, 11.4 SRU 89

• https://downloads.apache.org/httpd/CHANGES_2.4#2.4.66
• https://httpd.apache.org/security/vulnerabilities_24.html
• https://lists.apache.org/thread/1vygt5ztr7vqgtv9zclnln7mbwng6xzs

• Multiple vulnerabilities in Apache HTTP Server
• SUSE update for apache2
• Anolis OS update for httpd
• Red Hat Enterprise Linux 8 update for the httpd:2.4 module
• Red Hat Enterprise Linux 10 update for mod_md
• Red Hat Enterprise Linux 9 update for mod_md
• SUSE update for apache2
• Anolis OS update for httpd:2.4 module
• Red Hat Enterprise Linux 8 update for the httpd:2.4 module
• Red Hat Enterprise Linux 8 update for the httpd:2.4 module
• Red Hat Enterprise Linux 8 update for the httpd:2.4 module
• Red Hat Enterprise Linux 8 update for the httpd:2.4 module
• Red Hat Enterprise Linux 9 update for mod_md
• Red Hat Enterprise Linux 9 update for mod_md
• SUSE update for apache2
• SUSE update for apache2
• Red Hat Enterprise Linux 9 update for mod_md
• Red Hat Enterprise Linux 10 update for mod_md
• Ubuntu update for apache2
• Multiple vulnerabilities in Oracle Solaris
• openEuler 22.03 LTS SP4 update for httpd
• openEuler 20.03 LTS SP4 update for httpd
• openEuler 24.03 LTS SP1 update for httpd
• openEuler 24.03 LTS update for httpd
• Ubuntu update for apache2
• openEuler 24.03 LTS SP2 update for httpd
• Multiple vulnerabilities in Apple macOS Tahoe
• Multiple vulnerabilities in macOS Sequoia
• Multiple vulnerabilities in Apple macOS Sonoma
• Multiple vulnerabilities in IBM Cloud Object System
• Ubuntu update for apache2
• Ubuntu update for apache2
• Multiple vulnerabilities in IBM Cloud Pak System
• SUSE update for apache2
• Gentoo update for Apache HTTPD