USN-8571-2: Apache HTTP Server regression

USN-8571-1 fixed vulnerabilities in Apache HTTP Server. That fix was incomplete due to a missing library symbol, resulting in a regression that could cause Apache HTTP Server to fail to start when HTTP/2 proxying was enabled. This update fixes the problem. We apologize for the inconvenience. Original advisory details: Pavel Kohout and Arkadi Vainbrand discovered that Apache HTTP Server incorrectly handled certain memory operations in mod_authn_socache. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-33007) Haruki Oyama, Merih Mengisteab, and Dawit Jeong discovered that Apache HTTP Server had an HTTP response splitting vulnerability in multiple modules when used with untrusted or compromised backend servers. An attacker could possibly use this issue to inject arbitrary HTTP headers. (CVE-2026-33523) Elhanan Haenel discovered that Apache HTTP Server incorrectly handled certain memory operations in mod_proxy_ajp. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-33857) Tianshuo Han and Jérôme Djouder discovered that Apache HTTP Server incorrectly handled certain string operations in mod_proxy_ajp. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-34032) It was discovered that Apache HTTP Server's mod_proxy_html module incorrectly handled certain content from an untrusted backend. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-34355) It was discovered that Apache HTTP Server incorrectly handled ProxyPassReverseCookie directives with a malicious backend server. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-34356) It was discovered that Apache HTTP Server's mod_dav_fs module incorrectly handled certain path operations. An authenticated user could possibly use this issue to manipulate trusted WebDAV property databases or cause a denial of service. (CVE-2026-42535) It was discovered that Apache HTTP Server's mod_xml2enc module incorrectly handled certain content from an untrusted backend. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-42536) It was discovered that Apache HTTP Server incorrectly handled response headers when multiple content languages were configured. A remote attacker could possibly use this issue to obtain sen