Double free in Apache HTTP Server - CVE-2026-23918

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Main Vulnerability Database Vulnerabilities #VU129550

Double free in Apache HTTP Server - CVE-2026-23918

Published: May 4, 2026 / Updated: June 23, 2026


Vulnerability identifier: #VU129550
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-23918
CWE-ID: CWE-415
Exploitation vector: Remote access
Exploit availability: Public exploit is available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service and possibly execute arbitrary code.

The vulnerability exists due to a double free in Apache HTTP Server HTTP/2 handling when processing an early reset. A remote attacker can trigger an early reset condition to cause a denial of service and possibly execute arbitrary code.

The issue is specific to the HTTP/2 protocol.


Affected software

Apache HTTP Server
Gentoo Linux
Debian Linux
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
macOS
Basesystem Module
Server Applications Module
SUSE Package Hub 15
openSUSE Leap
Ubuntu
Anolis OS
SecurityCenter
apache2 (Ubuntu package)
apache2-debuginfo
apache2-tls13-example-pages
apache2
apache2-utils-debuginfo
apache2-tls13-worker-debuginfo
apache2-debugsource
apache2-devel
apache2-tls13-devel
apache2-prefork
apache2-tls13-prefork-debuginfo
apache2-worker
apache2-prefork-debuginfo
apache2-example-pages
apache2-tls13-debugsource
apache2-tls13-doc
apache2-doc
apache2-worker-debuginfo
apache2-tls13-utils
apache2-tls13-prefork
apache2-tls13-utils-debuginfo
apache2-tls13
apache2-tls13-debuginfo
apache2-utils
apache2-tls13-worker
apache2-event-debuginfo
apache2-event
apache2-manual
apache2-prefork-debugsource
apache2-utils-debugsource
apache2-worker-debugsource
apache2-event-debugsource
mod_ssl
httpd-filesystem
httpd
httpd-core
httpd-devel
httpd-tools
mod_ldap
mod_lua
mod_proxy_html
mod_session
httpd-doc
httpd-manual
apache2 (Debian package)
www-servers/apache

How to mitigate CVE-2026-23918

Install security update from vendor's website.

Apache HTTP Server - update to 2.4.67
SecurityCenter - addressed in versions SC202607.1, SC202607.2
macOS - addressed in versions 14.8.8 23J620, 15.7.8 24G824, 26.6 25G72
apache2 (Ubuntu package) - addressed in versions 2.4.52-1ubuntu4.20, 2.4.58-1ubuntu8.12, 2.4.64-1ubuntu3.4, 2.4.66-2ubuntu2.1
apache2-debuginfo - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-tls13-example-pages - update to 2.4.66-35.78.1
apache2 - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-utils-debuginfo - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-tls13-worker-debuginfo - update to 2.4.66-35.78.1
apache2-debugsource - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-devel - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-tls13-devel - update to 2.4.66-35.78.1
apache2-prefork - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-tls13-prefork-debuginfo - update to 2.4.66-35.78.1
apache2-worker - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-prefork-debuginfo - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-example-pages - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1
apache2-tls13-debugsource - update to 2.4.66-35.78.1
apache2-tls13-doc - update to 2.4.66-35.78.1
apache2-doc - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1
apache2-worker-debuginfo - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-tls13-utils - update to 2.4.66-35.78.1
apache2-tls13-prefork - update to 2.4.66-35.78.1
apache2-tls13-utils-debuginfo - update to 2.4.66-35.78.1
apache2-tls13 - update to 2.4.66-35.78.1
apache2-tls13-debuginfo - update to 2.4.66-35.78.1
apache2-utils - addressed in versions 2.4.66-35.78.1, 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-tls13-worker - update to 2.4.66-35.78.1
apache2-event-debuginfo - addressed in versions 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-event - addressed in versions 2.4.66-150400.6.57.1, 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-manual - addressed in versions 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-prefork-debugsource - addressed in versions 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-utils-debugsource - addressed in versions 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-worker-debugsource - addressed in versions 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
apache2-event-debugsource - addressed in versions 2.4.66-150600.5.52.1, 2.4.66-150700.4.20.1
mod_ssl - update to 2.4.67-1
httpd-filesystem - update to 2.4.67-1
httpd - update to 2.4.67-1
httpd-core - update to 2.4.67-1
httpd-devel - update to 2.4.67-1
httpd-tools - update to 2.4.67-1
mod_ldap - update to 2.4.67-1
mod_lua - update to 2.4.67-1
mod_proxy_html - update to 2.4.67-1
mod_session - update to 2.4.67-1
httpd-doc - update to 2.4.67-1
httpd-manual - update to 2.4.67-1
apache2 (Debian package) - addressed in versions 2.4.67-1~deb12u2, 2.4.67-1~deb13u2
www-servers/apache - update to 2.4.68

Links to Public Exploits and PoC-codes

External References

Related Security Bulletins