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".
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alma_linux | — | Upgrade httpd-filesystemUpgrade mod_http2Upgrade httpd-toolsUpgrade mod_ldapUpgrade mod_sslUpgrade mod_proxy_htmlUpgrade mod_sessionUpgrade httpd-manualUpgrade httpd-develUpgrade httpdUpgrade mod_md | Sep 3, 2025 | Sep 2, 2025 |
| Alpine Linux | — | Upgrade apache2 | Aug 8, 2025 | Jul 10, 2025 |
| Amazon Linux Ami 2 | — | Upgrade httpd-develUpgrade mod_proxy_htmlUpgrade mod_mdUpgrade httpdUpgrade httpd-toolsUpgrade mod_sslUpgrade mod_sessionUpgrade httpd-manualUpgrade httpd-debuginfoUpgrade httpd-filesystemUpgrade mod_ldap | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade mod_proxy_htmlUpgrade httpd-filesystemUpgrade mod_sessionUpgrade mod_ldapUpgrade mod_proxy_html-debuginfoUpgrade httpd-core-debuginfoUpgrade mod_session-debuginfoUpgrade mod_ssl-debuginfoUpgrade mod_ldap-debuginfoUpgrade mod_sslUpgrade httpd-debugsourceUpgrade httpd-manualUpgrade httpd-develUpgrade httpd-toolsUpgrade httpd-coreUpgrade mod_luaUpgrade httpdUpgrade httpd-tools-debuginfoUpgrade httpd-debuginfoUpgrade mod_lua-debuginfo | Aug 5, 2025 | Jul 14, 2025 |
| Apache Httpd | — | Upgrade to the latest version of Apache HTTPD | Jul 18, 2025 | Jul 10, 2025 |
| Debian | — | Upgrade apache2 | Jul 14, 2025 | Jul 10, 2025 |
| Freebsd | — | Upgrade mod_http2Upgrade apache24 | Jul 13, 2025 | Jul 11, 2025 |
| Gentoo Linux | — | Upgrade www-servers/apache. | Aug 16, 2026 | Aug 13, 2026 |
| Huawei Euleros 2_0_sp10 | — | Upgrade mod_http2 | Nov 12, 2025 | Oct 23, 2025 |
| Huawei Euleros 2_0_sp11 | — | Upgrade mod_http2 | Dec 12, 2025 | Oct 23, 2025 |
| Huawei Euleros 2_0_sp12 | — | Upgrade mod_http2 | Nov 12, 2025 | Oct 23, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade httpd-filesystemUpgrade httpd-toolsUpgrade httpdUpgrade mod_ssl | Oct 24, 2025 | Oct 23, 2025 |
| Oracle_linux | — | Upgrade mod_mdUpgrade httpdUpgrade httpd-manualUpgrade mod_sslUpgrade httpd-develUpgrade mod_proxy_htmlUpgrade mod_sessionUpgrade mod_ldapUpgrade mod_http2Upgrade httpd-toolsUpgrade httpd-filesystem | Aug 27, 2025 | Jul 14, 2025 |
| Redhat_linux | — | Upgrade mod_ldapUpgrade httpd-filesystemUpgrade httpd-tools-debuginfoUpgrade httpd-debugsourceUpgrade mod_http2Upgrade mod_proxy_html-debuginfoUpgrade mod_sessionUpgrade mod_session-debuginfoUpgrade httpd-toolsUpgrade mod_mdUpgrade httpd-develUpgrade mod_ldap-debuginfoUpgrade httpdUpgrade httpd-manualUpgrade mod_ssl-debuginfoUpgrade mod_sslUpgrade mod_http2-debugsourceUpgrade mod_proxy_htmlUpgrade httpd-debuginfoUpgrade mod_http2-debuginfoUpgrade mod_md-debugsourceUpgrade mod_md-debuginfo | Jul 15, 2025 | Jul 10, 2025 |
| Rocky_linux | — | Upgrade httpd-toolsUpgrade mod_ssl-debuginfoUpgrade mod_md-debugsourceUpgrade httpd-tools-debuginfoUpgrade mod_http2Upgrade mod_session-debuginfoUpgrade httpd-develUpgrade mod_md-debuginfoUpgrade mod_ldap-debuginfoUpgrade mod_http2-debugsourceUpgrade mod_sslUpgrade mod_mdUpgrade httpd-debugsourceUpgrade mod_http2-debuginfoUpgrade httpdUpgrade mod_proxy_html-debuginfoUpgrade mod_ldapUpgrade mod_sessionUpgrade mod_proxy_htmlUpgrade httpd-debuginfo | Feb 5, 2026 | Sep 8, 2025 |
| Suse | — | Upgrade apache2-develUpgrade apache2-tls13-docUpgrade apache2-manualUpgrade apache2-tls13-preforkUpgrade apache2-tls13-utilsUpgrade apache2Upgrade apache2-tls13-example-pagesUpgrade apache2-eventUpgrade apache2-tls13Upgrade apache2-example-pagesUpgrade apache2-workerUpgrade apache2-utilsUpgrade apache2-preforkUpgrade apache2-docUpgrade apache2-tls13-workerUpgrade apache2-tls13-devel | Dec 5, 2025 | Sep 2, 2025 |
| Ubuntu | — | Upgrade apache2 (Ubuntu Pro)Upgrade apache2 | Jul 17, 2025 | Jul 10, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Aug 11, 2025 | Jul 10, 2025 |
With curated Threat Intelligence, you can see which vulnerabilities truly put you at risk, prioritize what matters most, and act before attackers do.
Explore Intelligence Hub