An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.
This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.
Users are recommended to upgrade to version 2.4.58, which fixes the issue.
CVSS Details
- CVSS 3.1 Base Score: 7.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alma_linux | — | Upgrade mod_http2 | May 8, 2024 | Oct 23, 2023 |
| Alpine Linux | — | Upgrade apache2 | Mar 26, 2024 | Oct 23, 2023 |
| Amazon Linux Ami 2 | — | Upgrade httpd-debuginfoUpgrade httpd-develUpgrade mod_proxy_htmlUpgrade httpd-filesystemUpgrade httpd-manualUpgrade mod_sslUpgrade mod_sessionUpgrade httpd-toolsUpgrade httpdUpgrade mod_ldapUpgrade mod_md | Nov 3, 2023 | Oct 23, 2023 |
| Amazon_linux | — | Upgrade httpd24 | Nov 4, 2023 | Oct 23, 2023 |
| Amazon_linux_2023 | — | Upgrade httpd-core-debuginfoUpgrade httpd-manualUpgrade httpd-coreUpgrade mod_ssl-debuginfoUpgrade httpdUpgrade mod_lua-debuginfoUpgrade httpd-debugsourceUpgrade httpd-develUpgrade mod_ldap-debuginfoUpgrade httpd-toolsUpgrade httpd-filesystemUpgrade mod_proxy_htmlUpgrade httpd-tools-debuginfoUpgrade mod_sslUpgrade mod_proxy_html-debuginfoUpgrade mod_luaUpgrade mod_sessionUpgrade httpd-debuginfoUpgrade mod_ldapUpgrade mod_session-debuginfo | Feb 17, 2025 | Oct 10, 2023 |
| Apache Httpd | — | Upgrade to the latest version of Apache HTTPD | Nov 29, 2023 | Oct 23, 2023 |
| Debian | — | Upgrade apache2 | Apr 18, 2024 | Oct 23, 2023 |
| Freebsd | — | Upgrade apache24Upgrade varnish7 | Dec 10, 2025 | Oct 19, 2023 |
| Oracle_linux | — | Upgrade mod_http2 | May 8, 2024 | Oct 10, 2023 |
| Redhat_linux | — | Upgrade mod_http2-debugsourceUpgrade mod_http2Upgrade mod_http2-debuginfo | May 1, 2024 | Oct 23, 2023 |
| Ubuntu | — | Upgrade apache2 | Nov 23, 2023 | Oct 23, 2023 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Jan 20, 2025 | Oct 23, 2023 |
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