{"id":"CVE-2020-11996","aliases":["BIT-tomcat-2020-11996","GHSA-53hp-jpwq-2jgq"],"url":"https://o3.security/vulnerability/CVE-2020-11996","summary":"Uncontrolled Resource Consumption in Apache Tomcat","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.","published":"2020-06-26T17:15:10.153Z","modified":"2026-10-10T02:31:14.398398661Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.26699,"percentile":0.97847,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":2,"affectedPackages":[{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","fixedVersion":"10.0.0-M5"},{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","fixedVersion":"9.0.35"},{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","fixedVersion":"8.5.55"},{"ecosystem":"Maven","name":"org.apache.tomcat.embed:tomcat-embed-core","fixedVersion":"10.0.0-M5"},{"ecosystem":"Maven","name":"org.apache.tomcat.embed:tomcat-embed-core","fixedVersion":"9.0.35"},{"ecosystem":"Maven","name":"org.apache.tomcat.embed:tomcat-embed-core","fixedVersion":"8.5.55"}],"fix":{"url":"https://github.com/apache/tomcat/commit/9434a44d3449d620b1be70206819f8275b4a7509","label":"apache/tomcat@9434a44"},"references":[{"type":"WEB","url":"https://lists.apache.org/thread.html/r2529016c311ce9485e6f173446d469600fdfbb94dccadfcd9dfdac79%40%3Cusers.tomcat.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r3ea96d8f36dd404acce83df8aeb22a9e807d6c13ca9c5dec72f872cd%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r5a4f80a6acc6607d61dae424b643b594c6188dd4e1eff04705c10db2%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r6c29801370a36c1a5159679269777ad0c73276d3015b8bbefea66e5c%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d9fee3dc789dca9%40%3Ccommits.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff1057115008100561%40%3Ccommits.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r93ca628ef3a4530dfe5ac49fddc795f0920a4b2a408b57a30926a42b%40%3Ccommits.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r9ad911fe49450ed9405827af0e7a74104041081ff91864b1f2546bbd%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rb4ee49ecc4c59620ffd5e66e84a17e526c2c3cfa95d0cd682d90d338%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rb820f1a2a02bf07414be12c653c2ab5321fd87b9bf6c5e635c53ff4b%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/ref0339792ac6dac1dba83c071a727ad72380899bde60f6aaad4031b9%40%3Cnotifications.ofbiz.apache.org%3E"},{"type":"ADVISORY","url":"http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00064.html"},{"type":"ADVISORY","url":"http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00072.html"},{"type":"ADVISORY","url":"https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E"},{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2020/07/msg00010.html"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20200709-0002/"},{"type":"ADVISORY","url":"https://usn.ubuntu.com/4596-1/"},{"type":"ADVISORY","url":"https://www.debian.org/security/2020/dsa-4727"},{"type":"ADVISORY","url":"https://www.oracle.com/security-alerts/cpujan2021.html"},{"type":"ADVISORY","url":"https://www.oracle.com/security-alerts/cpuoct2020.html"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-11996"},{"type":"WEB","url":"https://github.com/apache/tomcat/commit/9434a44d3449d620b1be70206819f8275b4a7509"},{"type":"WEB","url":"https://github.com/apache/tomcat/commit/9a0231683a77e2957cea0fdee88b193b30b0c976"},{"type":"WEB","url":"https://github.com/apache/tomcat/commit/c8acd2ab7371e39aeca7c306f3b5380f00afe552"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rb820f1a2a02bf07414be12c653c2ab5321fd87b9bf6c5e635c53ff4b@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542@%3Cnotifications.ofbiz.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52@%3Cnotifications.ofb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