{"id":"UBUNTU-CVE-2020-11996","details":"A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server could become unresponsive.","modified":"2026-07-15T19:45:17.398396144Z","published":"2020-06-26T17:15:00Z","related":["USN-4596-1"],"upstream":["CVE-2020-11996"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-11996"},{"type":"REPORT","url":"https://www.openwall.com/lists/oss-security/2020/06/25/6"},{"type":"REPORT","url":"https://github.com/apache/tomcat/commit/9a0231683a77e2957cea0fdee88b193b30b0c976"},{"type":"REPORT","url":"https://github.com/apache/tomcat/commit/c8acd2ab7371e39aeca7c306f3b5380f00afe552"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d9fee3dc789dca9@%3Ccommits.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff1057115008100561@%3Ccommits.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/r93ca628ef3a4530dfe5ac49fddc795f0920a4b2a408b57a30926a42b@%3Ccommits.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/rb4ee49ecc4c59620ffd5e66e84a17e526c2c3cfa95d0cd682d90d338@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/rb820f1a2a02bf07414be12c653c2ab5321fd87b9bf6c5e635c53ff4b@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"REPORT","url":"https://lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-4596-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-11996"}],"affected":[{"package":{"name":"tomcat8","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/tomcat8?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.5.21-1ubuntu1","8.5.29-1","8.5.30-1","8.5.30-1ubuntu1","8.5.30-1ubuntu1.2","8.5.30-1ubuntu1.3","8.5.30-1ubuntu1.4","8.5.39-1ubuntu1~18.04.1","8.5.39-1ubuntu1~18.04.2","8.5.39-1ubuntu1~18.04.3","8.5.39-1ubuntu1~18.04.3+esm1","8.5.39-1ubuntu1~18.04.3+esm2","8.5.39-1ubuntu1~18.04.3+esm3","8.5.39-1ubuntu1~18.04.3+esm4","8.5.39-1ubuntu1~18.04.3+esm5","8.5.39-1ubuntu1~18.04.3+esm6"],"ecosystem_specific":{"binaries":[{"binary_name":"libtomcat8-embed-java","binary_version":"8.5.39-1ubuntu1~18.04.3+esm6"},{"binary_name":"libtomcat8-java","binary_version":"8.5.39-1ubuntu1~18.04.3+esm6"},{"binary_name":"tomcat8","binary_version":"8.5.39-1ubuntu1~18.04.3+esm6"},{"binary_name":"tomcat8-admin","binary_version":"8.5.39-1ubuntu1~18.04.3+esm6"},{"binary_version":"8.5.39-1ubuntu1~18.04.3+esm6","binary_name":"tomcat8-common"},{"binary_name":"tomcat8-docs","binary_version":"8.5.39-1ubuntu1~18.04.3+esm6"},{"binary_name":"tomcat8-examples","binary_version":"8.5.39-1ubuntu1~18.04.3+esm6"},{"binary_version":"8.5.39-1ubuntu1~18.04.3+esm6","binary_name":"tomcat8-user"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-11996.json"}},{"package":{"name":"tomcat9","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/tomcat9?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.0.16-3~18.04.1","9.0.16-3ubuntu0.18.04.1","9.0.16-3ubuntu0.18.04.2","9.0.16-3ubuntu0.18.04.2+esm1","9.0.16-3ubuntu0.18.04.2+esm2","9.0.16-3ubuntu0.18.04.2+esm3","9.0.16-3ubuntu0.18.04.2+esm4","9.0.16-3ubuntu0.18.04.2+esm5","9.0.16-3ubuntu0.18.04.2+esm6","9.0.16-3ubuntu0.18.04.2+esm7","9.0.16-3ubuntu0.18.04.2+esm8"],"ecosystem_specific":{"binaries":[{"binary_version":"9.0.16-3ubuntu0.18.04.2+esm8","binary_name":"libtomcat9-embed-java"},{"binary_name":"libtomcat9-java","binary_version":"9.0.16-3ubuntu0.18.04.2+esm8"},{"binary_name":"tomcat9","binary_version":"9.0.16-3ubuntu0.18.04.2+esm8"},{"binary_version":"9.0.16-3ubuntu0.18.04.2+esm8","binary_name":"tomcat9-admin"},{"binary_name":"tomcat9-common","binary_version":"9.0.16-3ubuntu0.18.04.2+esm8"},{"binary_version":"9.0.16-3ubuntu0.18.04.2+esm8","binary_name":"tomcat9-docs"},{"binary_version":"9.0.16-3ubuntu0.18.04.2+esm8","binary_name":"tomcat9-examples"},{"binary_version":"9.0.16-3ubuntu0.18.04.2+esm8","binary_name":"tomcat9-user"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-11996.json"}},{"package":{"name":"tomcat9","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/tomcat9?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"9.0.31-1ubuntu0.1"}]}],"versions":["9.0.24-1","9.0.27-1","9.0.31-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libtomcat9-embed-java","binary_version":"9.0.31-1ubuntu0.1"},{"binary_name":"libtomcat9-java","binary_version":"9.0.31-1ubuntu0.1"},{"binary_version":"9.0.31-1ubuntu0.1","binary_name":"tomcat9"},{"binary_version":"9.0.31-1ubuntu0.1","binary_name":"tomcat9-admin"},{"binary_name":"tomcat9-common","binary_version":"9.0.31-1ubuntu0.1"},{"binary_version":"9.0.31-1ubuntu0.1","binary_name":"tomcat9-docs"},{"binary_name":"tomcat9-examples","binary_version":"9.0.31-1ubuntu0.1"},{"binary_name":"tomcat9-user","binary_version":"9.0.31-1ubuntu0.1"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-11996.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"},{"type":"Ubuntu","score":"medium"}]}