--- id: CVE-2020-11996 title: >- 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 summary: >- 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 c… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' vendor: apache product: tomcat affected: - 'tomcat >= 8.5.0, <= 8.5.55' - 'tomcat >= 9.0.0, <= 9.0.35' - tomcat = 9.0.0 - tomcat = 10.0.0 - ubuntu_linux = 20.04 - mysql_enterprise_monitor <= 8.0.21 - siebel_ui_framework <= 20.12 - workload_manager = 12.2.0.1 - workload_manager = 18c - workload_manager = 19c - leap = 15.1 - leap = 15.2 - debian_linux = 9.0 - debian_linux = 10.0 - oncommand_system_manager = 3.0 - oncommand_system_manager = 3.1.3 published: '2020-06-26' updated: '2026-10-08' sourceUpdated: '2026-10-08T22:16:56.027' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-11996' references: - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00064.html' label: security@apache.org - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00072.html' label: security@apache.org - url: >- https://lists.apache.org/thread.html/r2529016c311ce9485e6f173446d469600fdfbb94dccadfcd9dfdac79%40%3Cusers.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r3ea96d8f36dd404acce83df8aeb22a9e807d6c13ca9c5dec72f872cd%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r5a4f80a6acc6607d61dae424b643b594c6188dd4e1eff04705c10db2%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r6c29801370a36c1a5159679269777ad0c73276d3015b8bbefea66e5c%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d9fee3dc789dca9%40%3Ccommits.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff1057115008100561%40%3Ccommits.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r93ca628ef3a4530dfe5ac49fddc795f0920a4b2a408b57a30926a42b%40%3Ccommits.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r9ad911fe49450ed9405827af0e7a74104041081ff91864b1f2546bbd%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rb4ee49ecc4c59620ffd5e66e84a17e526c2c3cfa95d0cd682d90d338%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rb820f1a2a02bf07414be12c653c2ab5321fd87b9bf6c5e635c53ff4b%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/ref0339792ac6dac1dba83c071a727ad72380899bde60f6aaad4031b9%40%3Cnotifications.ofbiz.apache.org%3E label: security@apache.org - url: 'https://lists.debian.org/debian-lts-announce/2020/07/msg00010.html' label: security@apache.org - url: 'https://security.netapp.com/advisory/ntap-20200709-0002/' label: security@apache.org - url: 'https://usn.ubuntu.com/4596-1/' label: security@apache.org - url: 'https://www.debian.org/security/2020/dsa-4727' label: security@apache.org - url: 'https://www.oracle.com/security-alerts/cpujan2021.html' label: security@apache.org - url: 'https://www.oracle.com/security-alerts/cpuoct2020.html' label: security@apache.org - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00064.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00072.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r2529016c311ce9485e6f173446d469600fdfbb94dccadfcd9dfdac79%40%3Cusers.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r3ea96d8f36dd404acce83df8aeb22a9e807d6c13ca9c5dec72f872cd%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r5a4f80a6acc6607d61dae424b643b594c6188dd4e1eff04705c10db2%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r6c29801370a36c1a5159679269777ad0c73276d3015b8bbefea66e5c%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d9fee3dc789dca9%40%3Ccommits.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff1057115008100561%40%3Ccommits.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r93ca628ef3a4530dfe5ac49fddc795f0920a4b2a408b57a30926a42b%40%3Ccommits.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r9ad911fe49450ed9405827af0e7a74104041081ff91864b1f2546bbd%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rb4ee49ecc4c59620ffd5e66e84a17e526c2c3cfa95d0cd682d90d338%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rb820f1a2a02bf07414be12c653c2ab5321fd87b9bf6c5e635c53ff4b%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/ref0339792ac6dac1dba83c071a727ad72380899bde60f6aaad4031b9%40%3Cnotifications.ofbiz.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2020/07/msg00010.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://security.netapp.com/advisory/ntap-20200709-0002/' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://usn.ubuntu.com/4596-1/' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.debian.org/security/2020/dsa-4727' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpujan2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuoct2020.html' label: af854a3a-2127-422b-91ae-364da2661108 tags: - nvd - exploit-available epss: 0.26699 epssPercentile: 0.97981 exploits: github: 1 githubRepos: - 'https://github.com/rusakovichma/tomcat-embed-core-9.0.31-CVE-2020-11996' checkedAt: '2026-10-08T23:17:21.746Z' exploitAvailable: true ingestedAt: '2026-10-08T23:16:47.307Z' --- ## Overview 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. ## Affected - `tomcat >= 8.5.0, <= 8.5.55` - `tomcat >= 9.0.0, <= 9.0.35` - `tomcat = 9.0.0` - `tomcat = 10.0.0` - `ubuntu_linux = 20.04` - `mysql_enterprise_monitor <= 8.0.21` - `siebel_ui_framework <= 20.12` - `workload_manager = 12.2.0.1` - `workload_manager = 18c` - `workload_manager = 19c` - `leap = 15.1` - `leap = 15.2` - `debian_linux = 9.0` - `debian_linux = 10.0` - `oncommand_system_manager = 3.0` - `oncommand_system_manager = 3.1.3` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges.