{"id":"CVE-2021-31618","details":"Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released.","aliases":["BIT-apache-2021-31618"],"modified":"2026-04-16T04:39:12.680528427Z","published":"2021-06-15T09:15:07.960Z","related":["SUSE-SU-2021:2004-1","SUSE-SU-2021:2006-1","SUSE-SU-2021:2127-1","openSUSE-SU-2021:0908-1","openSUSE-SU-2021:2127-1"],"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A73QJ4HPUMU26I6EULG6SCK67TUEXZYR/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2NKJ3ZA3FTSZ2QBBPKS6BYGAWYRABNQQ/"},{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2024/03/13/2"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r14b66ef0f4f569fd515a3f96cd4eb58bd9a8ff525cc326bb0359664f%40%3Ccvs.httpd.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r783b6558abf3305b17ea462bed4bd66d82866438999bf38cef6d11d1%40%3Ccvs.httpd.apache.org%3E"},{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2021/07/msg00006.html"},{"type":"ADVISORY","url":"https://seclists.org/oss-sec/2021/q2/206"},{"type":"ADVISORY","url":"https://security.gentoo.org/glsa/202107-38"},{"type":"ADVISORY","url":"http://www.openwall.com/lists/oss-security/2021/06/10/9"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20210727-0008/"},{"type":"ADVISORY","url":"https://www.debian.org/security/2021/dsa-4937"},{"type":"ADVISORY","url":"http://httpd.apache.org/security/vulnerabilities_24.html"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpuoct2021.html"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/apache/httpd","events":[{"introduced":"0"},{"last_affected":"f442d2ad7489aa917a6113d016805dbd110b706c"}],"database_specific":{"versions":[{"introduced":"0"},{"last_affected":"2.4.47"}]}}],"versions":["2.4.47"],"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"1.15.17"}]},{"events":[{"introduced":"0"},{"last_affected":"33"}]},{"events":[{"introduced":"0"},{"last_affected":"34"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0"}]},{"events":[{"introduced":"0"},{"last_affected":"10.0"}]},{"events":[{"introduced":"0"},{"last_affected":"12.4.0.0"}]},{"events":[{"introduced":"0"},{"last_affected":"17.1"}]},{"events":[{"introduced":"0"},{"last_affected":"17.2"}]},{"events":[{"introduced":"0"},{"last_affected":"17.3"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-31618.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}