{"id":"CVE-2021-31618","aliases":["ALPINE-CVE-2021-31618","AZL-44166","BELL-CVE-2021-31618","BIT-apache-2021-31618","DEBIAN-CVE-2021-31618","DLA-2706-1","DSA-4937-1","EUVD-2021-18507","GHSA-4jq3-qrx6-87cc","MGASA-2021-0265","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"],"status":"published","title":"NULL pointer dereference on specially crafted HTTP/2 request","description":"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.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.52142,"percentile":0.98975,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-476"],"published":"2021-06-15T00:00:00Z","modified":"2026-10-24T10:30:15Z","fixes":[{"ecosystem":"Alpine:v3.10","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.11","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.12","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.13","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.14","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.15","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.16","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.17","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.18","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.19","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.20","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.21","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.22","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.23","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"apache2","fixed_in":["2.4.48-r0"],"sources":["osv"]},{"ecosystem":"Azure Linux:3","package":"mod_http2","fixed_in":["2.0.29-3"],"sources":["osv"]},{"ecosystem":"Bitnami","package":"apache","fixed_in":["1.15.18","2.4.48"],"sources":["osv"]},{"ecosystem":"Debian:12","package":"apache2","fixed_in":["2.4.46-5"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"apache2","fixed_in":["2.4.46-5"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"apache2","fixed_in":["2.4.46-5"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Alpine:v3.10","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.11","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.12","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.13","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.14","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.15","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.16","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.17","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.18","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.19","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.20","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.21","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.22","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-r0"}]}]},{"source":"osv","ecosystem":"Azure Linux:3","package":"mod_http2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.29-3"}]}]},{"source":"osv","ecosystem":"Bitnami","package":"apache","ranges":[{"type":"SEMVER","events":[{"introduced":"1.15.17"},{"fixed":"1.15.18"},{"introduced":"2.4.47"},{"fixed":"2.4.48"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.46-5"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.46-5"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.46-5"}]}]},{"source":"osv","ecosystem":"Debian:9","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.25-3+deb9u10"}]}],"versions":["2.4.25-3","2.4.25-3+deb9u1","2.4.25-3+deb9u2","2.4.25-3+deb9u3","2.4.25-3+deb9u4","2.4.25-3+deb9u5","2.4.25-3+deb9u6","2.4.25-3+deb9u7","2.4.25-3+deb9u8","2.4.25-3+deb9u9"],"bundled":7},{"source":"osv","ecosystem":"Debian:10","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.38-3+deb10u5"}]}],"versions":["2.4.38-3","2.4.38-3+deb10u1","2.4.38-3+deb10u2","2.4.38-3+deb10u3","2.4.38-3+deb10u4"],"bundled":5},{"source":"osv","ecosystem":"Mageia:7","package":"apache","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-1.mga7"}]}],"bundled":7},{"source":"osv","ecosystem":"Mageia:8","package":"apache","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.48-1.mga8"}]}],"bundled":7},{"source":"osv","ecosystem":"SUSE:Linux Enterprise High Performance Computing 15-ESPOS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise High Performance Computing 15-LTSS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 15-LTSS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 15 SP1-BCL","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 15 SP1-LTSS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 15","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 15 SP1","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Manager Proxy 4.0","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Manager Retail Branch Server 4.0","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Manager Server 4.0","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Enterprise Storage 6","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.33-3.50.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:HPE Helion OpenStack 8","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:OpenStack Cloud 8","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:OpenStack Cloud 9","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:OpenStack Cloud Crowbar 8","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:OpenStack Cloud Crowbar 9","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 12 SP3","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 12 SP4","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Software Development Kit 12 SP5","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 12 SP2-BCL","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 12 SP3-LTSS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 12 SP3-BCL","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 12 SP4-LTSS","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 12 SP5","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 12 SP5","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.23-29.74.1"}]}],"bundled":5},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Basesystem 15 SP2","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-3.22.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Basesystem 15 SP3","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-3.22.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Package Hub 15 SP3","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-3.22.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Server Applications 15 SP2","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-3.22.1"}]}],"bundled":6},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Server Applications 15 SP3","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-3.22.1"}]}],"bundled":6},{"source":"osv","ecosystem":"openSUSE:Leap 15.2","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-lp152.2.15.1"}]}],"bundled":6},{"source":"osv","ecosystem":"openSUSE:Leap 15.3","package":"apache2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.43-3.22.1"}]}],"bundled":6}],"products":[{"vendor":"apache","product":"http_server"},{"vendor":"apache software foundation","product":"apache http server"},{"vendor":"debian","product":"debian_linux"},{"vendor":"fedoraproject","product":"fedora"},{"vendor":"oracle","product":"enterprise_manager_ops_center"},{"vendor":"oracle","product":"instantis_enterprisetrack"},{"vendor":"oracle","product":"zfs_storage_appliance_kit"}],"references":[{"url":"http://httpd.apache.org/security/vulnerabilities_24.html","tags":["x_transferred","Release Notes","Vendor Advisory","advisory"]},{"url":"http://www.openwall.com/lists/oss-security/2021/06/10/9","tags":["mailing-list","x_transferred","Mailing List","Third Party Advisory","advisory"]},{"url":"https://seclists.org/oss-sec/2021/q2/206","tags":["x_transferred","Mailing List","Third Party Advisory","advisory"]},{"url":"https://lists.apache.org/thread.html/r14b66ef0f4f569fd515a3f96cd4eb58bd9a8ff525cc326bb0359664f%40%3Ccvs.httpd.apache.org%3E","tags":["mailing-list","x_transferred","web"]},{"url":"https://lists.apache.org/thread.html/r783b6558abf3305b17ea462bed4bd66d82866438999bf38cef6d11d1%40%3Ccvs.httpd.apache.org%3E","tags":["mailing-list","x_transferred","web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2NKJ3ZA3FTSZ2QBBPKS6BYGAWYRABNQQ/","tags":["vendor-advisory","x_transferred","web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A73QJ4HPUMU26I6EULG6SCK67TUEXZYR/","tags":["vendor-advisory","x_transferred","web"]},{"url":"https://lists.debian.org/debian-lts-announce/2021/07/msg00006.html","tags":["mailing-list","x_transferred","Mailing List","Third Party Advisory","advisory"]},{"url":"https://www.debian.org/security/2021/dsa-4937","tags":["vendor-advisory","x_transferred","Third Party Advisory","advisory"]},{"url":"https://security.gentoo.org/glsa/202107-38","tags":["vendor-advisory","x_transferred","Third Party Advisory","advisory"]},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","tags":["x_transferred","Patch","Third Party Advisory","advisory","fix"]},{"url":"https://security.netapp.com/advisory/ntap-20210727-0008/","tags":["x_transferred","Third Party Advisory","advisory"]},{"url":"http://www.openwall.com/lists/oss-security/2024/03/13/2","tags":["mailing-list","x_transferred","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-31618","tags":["web"]},{"url":"https://lists.apache.org/thread.html/r14b66ef0f4f569fd515a3f96cd4eb58bd9a8ff525cc326bb0359664f@%3Ccvs.httpd.apache.org%3E"},{"url":"https://lists.apache.org/thread.html/r783b6558abf3305b17ea462bed4bd66d82866438999bf38cef6d11d1@%3Ccvs.httpd.apache.org%3E"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2NKJ3ZA3FTSZ2QBBPKS6BYGAWYRABNQQ"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A73QJ4HPUMU26I6EULG6SCK67TUEXZYR"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2NKJ3ZA3FTSZ2QBBPKS6BYGAWYRABNQQ"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/A73QJ4HPUMU26I6EULG6SCK67TUEXZYR"},{"url":"https://security.netapp.com/advisory/ntap-20210727-0008"},{"url":"https://github.com/advisories/GHSA-4jq3-qrx6-87cc"},{"url":"https://security.alpinelinux.org/vuln/CVE-2021-31618","tags":["advisory"]},{"url":"https://docs.bell-sw.com/security/cves/CVE-2021-31618","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-31618","tags":["advisory"]},{"url":"https://advisories.mageia.org/MGASA-2021-0265.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=29087","tags":["report"]},{"url":"https://httpd.apache.org/security/vulnerabilities_24.html","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2021/suse-su-20212004-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1145740","tags":["report"]},{"url":"https://bugzilla.suse.com/1180530","tags":["report"]},{"url":"https://bugzilla.suse.com/1182703","tags":["report"]},{"url":"https://bugzilla.suse.com/1186922","tags":["report"]},{"url":"https://bugzilla.suse.com/1186923","tags":["report"]},{"url":"https://bugzilla.suse.com/1186924","tags":["report"]},{"url":"https://bugzilla.suse.com/1187017","tags":["report"]},{"url":"https://bugzilla.suse.com/1187174","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2019-10092","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2020-35452","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2021-26690","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2021-26691","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2021-30641","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2021-31618","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2021/suse-su-20212006-1/","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2021/suse-su-20212127-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1187040","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2020-13950","tags":["web"]},{"url":"https://lists.opensuse.org/archives/list/security-announce@lists.opensuse.org/thread/F32WQ7K6A45WOBEDFMGMRXDC2F2SL3IF/","tags":["advisory"]},{"url":"https://lists.opensuse.org/archives/list/security-announce@lists.opensuse.org/thread/KAQGPGA6ZQQT3VO5WOYFSSTZFH57MPWK/","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2021-31618","title":"NULL pointer dereference on specially crafted HTTP/2 request","description":"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.","status":"published","published":"2021-06-15T00:00:00Z","modified":"2024-08-03T23:03:33.651Z","cwes":["CWE-476"],"updated_at":"2026-11-02T14:33:05.665371Z"}],"euvd":[{"id":"EUVD-2021-18507","description":"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.","status":"published","published":"2021-06-15T00:00:00Z","modified":"2024-08-03T23:03:33Z","updated_at":"2026-11-03T03:24:38.423371Z"}],"ghsa":[{"id":"GHSA-4jq3-qrx6-87cc","title":"Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers...","description":"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.","status":"published","published":"2022-05-24T19:05:24Z","modified":"2024-05-11T05:02:49Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-476"],"updated_at":"2026-11-02T14:57:20.80512Z"}],"nvd":[{"id":"CVE-2021-31618","description":"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.","status":"published","published":"2021-06-15T09:15:07.96Z","modified":"2026-06-17T03:52:05.437Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-476"],"updated_at":"2026-11-02T14:06:54.892562Z"}],"osv":[{"id":"ALPINE-CVE-2021-31618","description":"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.","status":"published","published":"2021-06-15T09:15:07.96Z","modified":"2026-10-23T17:17:56.185243487Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:27:48.646074Z"},{"id":"AZL-44166","title":"CVE-2021-31618 affecting package mod_http2 for versions less than 2.0.29-3","description":"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.","status":"published","published":"2021-06-15T09:15:07Z","modified":"2026-04-21T04:54:25.550195Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:28:05.284713Z"},{"id":"BELL-CVE-2021-31618","title":"CVE-2021-31618 does not affect BellSoft software","status":"withdrawn","published":"2023-08-31T12:13:52.127453Z","modified":"2026-01-26T09:48:19.803753Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:28:16.5265Z"},{"id":"CVE-2021-31618","description":"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.","status":"published","published":"2021-06-15T09:15:07.96Z","modified":"2026-10-24T10:30:15.112250391Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:19.483607Z"},{"id":"DEBIAN-CVE-2021-31618","description":"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.","status":"published","published":"2021-06-15T09:15:07.96Z","modified":"2026-10-23T18:03:14.230016757Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:34.94143Z"},{"id":"BIT-apache-2021-31618","title":"NULL pointer dereference on specially crafted HTTP/2 request","description":"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.","status":"published","published":"2024-03-06T10:55:51.283Z","modified":"2026-09-08T08:45:06.507962153Z","updated_at":"2026-11-02T15:28:28.267217Z"},{"id":"DLA-2706-1","title":"apache2 - security update","status":"published","published":"2021-07-09T00:00:00Z","modified":"2026-03-09T01:02:00.348113Z","updated_at":"2026-11-02T15:46:10.712745Z"},{"id":"DSA-4937-1","title":"apache2 - security update","status":"published","published":"2021-07-08T00:00:00Z","modified":"2026-03-09T02:09:11.184377Z","updated_at":"2026-11-02T15:46:17.19998Z"},{"id":"MGASA-2021-0265","title":"Updated apache packages fix security vulnerabilities","description":"mod_proxy_wstunnel tunneling of non Upgraded connections: Apache HTTP Server \nversions 2.4.6 to 2.4.46 mod_proxy_wstunnel configured on an URL that is not \nnecessarily Upgraded by the origin server was tunneling the whole connection \nregardless, thus allowing for subsequent requests on the same connection to \npass through with no HTTP validation, authentication or authorization \npossibly configured. (CVE-2019-17567).\n   \nmod_proxy_http NULL pointer dereference: Apache HTTP Server versions 2.4.41 \nto 2.4.46 mod_proxy_http can be made to crash (NULL pointer dereference) with \nspecially crafted requests using both Content-Length and Transfer-Encoding \nheaders, leading to a Denial of Service (CVE-2020-13950).\n\nmod_auth_digest possible stack overflow by one nul byte: Apache HTTP Server \nversions 2.4.0 to 2.4.46 A specially crafted Digest nonce can cause a stack \noverflow in mod_auth_digest. There is no report of this overflow being \nexploitable, nor the Apache HTTP Server team could create one, though some \nparticular compiler and/or compilation option might make it possible, with \nlimited consequences anyway due to the size (a single byte) and the value \n(zero byte) of the overflow (CVE-2020-35452).\n\nmod_session NULL pointer dereference: Apache HTTP Server versions 2.4.0 to \n2.4.46 A specially crafted Cookie header handled by mod_session can cause a \nNULL pointer dereference and crash, leading to a possible Denial Of Service \n(CVE-2021-26690).\n\nmod_session response handling heap overflow: Apache HTTP Server versions \n2.4.0 to 2.4.46 A specially crafted SessionHeader sent by an origin server \ncould cause a heap overflow (CVE-2021-26691).\n\nUnexpected URL matching with 'MergeSlashes OFF': Apache HTTP Server versions \n2.4.39 to 2.4.46 Unexpected matching behavior with 'MergeSlashes \nOFF'(CVE-2021-30641).\n\nNULL pointer dereference on specially crafted HTTP/2 request: Apache HTTP \nServer protocol handler for the HTTP/2 protocol checks received request \nheaders against the size limitations as configured for the server and used \nfor the HTTP/1 protocol as well. On violation of these restrictions and HTTP \nresponse is sent to the client with a status code indicating why the request \nwas rejected. This rejection response was not fully initialised in the HTTP/2 \nprotocol handler if the offending header was the very first one received or \nappeared in a footer. This led to a NULL pointer dereference on initialised \nmemory, crashing reliably the child process. Since such a triggering HTTP/2 \nrequest is easy to craft and submit, this can be exploited to DoS the server. \nThis issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 \nonly. Apache HTTP Server 2.4.47 was never released. (CVE-2021-31618).\n","status":"published","published":"2021-06-16T20:22:25Z","modified":"2026-04-16T04:44:03.928538971Z","updated_at":"2026-11-02T15:49:41.509337Z"},{"id":"openSUSE-SU-2021:0908-1","title":"Security update for apache2","description":"This update for apache2 fixes the following issues:\n\n- fixed CVE-2021-30641 [bsc#1187174]: MergeSlashes regression\n- fixed CVE-2021-31618 [bsc#1186924]: NULL pointer dereference on specially crafted HTTP/2 request\n- fixed CVE-2020-13950 [bsc#1187040]: mod_proxy NULL pointer dereference\n- fixed CVE-2020-35452 [bsc#1186922]: Single zero byte stack overflow in mod_auth_digest \n- fixed CVE-2021-26690 [bsc#1186923]: mod_session NULL pointer dereference in parser\n- fixed CVE-2021-26691 [bsc#1187017]: Heap overflow in mod_session\n","status":"published","published":"2021-06-24T09:52:47Z","modified":"2026-02-04T03:49:43.716266Z","updated_at":"2026-11-02T16:58:31.879684Z"},{"id":"openSUSE-SU-2021:2127-1","title":"Security update for apache2","description":"This update for apache2 fixes the following issues:\n\n- fixed CVE-2021-30641 [bsc#1187174]: MergeSlashes regression\n- fixed CVE-2021-31618 [bsc#1186924]: NULL pointer dereference on specially crafted HTTP/2 request\n- fixed CVE-2020-13950 [bsc#1187040]: mod_proxy NULL pointer dereference\n- fixed CVE-2020-35452 [bsc#1186922]: Single zero byte stack overflow in mod_auth_digest \n- fixed CVE-2021-26690 [bsc#1186923]: mod_session NULL pointer dereference in parser\n- fixed CVE-2021-26691 [bsc#1187017]: Heap overflow in mod_session\n","status":"published","published":"2021-07-10T13:52:30Z","modified":"2026-02-04T02:55:40.053532Z","updated_at":"2026-11-02T16:58:32.266854Z"},{"id":"SUSE-SU-2021:2004-1","title":"Security update for apache2","description":"This update for apache2 fixes the following issues:\n\n- CVE-2021-30641: Fixed MergeSlashes regression (bsc#1187174)\n- CVE-2021-31618: Fixed NULL pointer dereference on specially crafted HTTP/2 request (bsc#1186924)\n- CVE-2020-35452: Fixed Single zero byte stack overflow in mod_auth_digest (bsc#1186922)\n- CVE-2021-26690: Fixed mod_session NULL pointer dereference in parser (bsc#1186923)\n- CVE-2021-26691: Fixed Heap overflow in mod_session (bsc#1187017)\n- Fixed potential content spoofing with default error pages (bsc#1182703)\n- Fixed for an issue when 'gensslcert' does not set CA:True. (bsc#1180530)\n","status":"published","published":"2021-06-17T16:03:59Z","modified":"2026-02-04T04:20:04.094533Z","updated_at":"2026-11-02T15:53:49.138643Z"},{"id":"SUSE-SU-2021:2006-1","title":"Security update for apache2","description":"This update for apache2 fixes the following issues:\n\n- fixed CVE-2021-30641 [bsc#1187174]: MergeSlashes regression\n- fixed CVE-2021-31618 [bsc#1186924]: NULL pointer dereference on specially crafted HTTP/2 request\n- fixed CVE-2020-35452 [bsc#1186922]: Single zero byte stack overflow in mod_auth_digest \n- fixed CVE-2021-26690 [bsc#1186923]: mod_session NULL pointer dereference in parser\n- fixed CVE-2021-26691 [bsc#1187017]: Heap overflow in mod_session\n","status":"published","published":"2021-06-17T16:06:42Z","modified":"2026-02-04T02:13:51.469341Z","updated_at":"2026-11-02T15:53:49.138643Z"},{"id":"SUSE-SU-2021:2127-1","title":"Security update for apache2","description":"This update for apache2 fixes the following issues:\n\n- fixed CVE-2021-30641 [bsc#1187174]: MergeSlashes regression\n- fixed CVE-2021-31618 [bsc#1186924]: NULL pointer dereference on specially crafted HTTP/2 request\n- fixed CVE-2020-13950 [bsc#1187040]: mod_proxy NULL pointer dereference\n- fixed CVE-2020-35452 [bsc#1186922]: Single zero byte stack overflow in mod_auth_digest \n- fixed CVE-2021-26690 [bsc#1186923]: mod_session NULL pointer dereference in parser\n- fixed CVE-2021-26691 [bsc#1187017]: Heap overflow in mod_session\n","status":"published","published":"2021-06-22T14:41:02Z","modified":"2026-02-04T03:13:18.563118Z","updated_at":"2026-11-02T15:53:49.138643Z"}]}}