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  5. CVE-2020-11996

CVE-2020-11996: Uncontrolled Resource Consumption in Apache Tomcat

February 9, 2022 (updated June 11, 2026)

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.

References

  • github.com/advisories/GHSA-53hp-jpwq-2jgq
  • github.com/apache/tomcat/commit/9434a44d3449d620b1be70206819f8275b4a7509
  • github.com/apache/tomcat/commit/9a0231683a77e2957cea0fdee88b193b30b0c976
  • github.com/apache/tomcat/commit/c8acd2ab7371e39aeca7c306f3b5380f00afe552
  • lists.apache.org/thread.html/r2529016c311ce9485e6f173446d469600fdfbb94dccadfcd9dfdac79@%3Cusers.tomcat.apache.org%3E
  • lists.apache.org/thread.html/r3ea96d8f36dd404acce83df8aeb22a9e807d6c13ca9c5dec72f872cd@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E
  • lists.apache.org/thread.html/r5a4f80a6acc6607d61dae424b643b594c6188dd4e1eff04705c10db2@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r6c29801370a36c1a5159679269777ad0c73276d3015b8bbefea66e5c@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d9fee3dc789dca9@%3Ccommits.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff1057115008100561@%3Ccommits.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r93ca628ef3a4530dfe5ac49fddc795f0920a4b2a408b57a30926a42b@%3Ccommits.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/r9ad911fe49450ed9405827af0e7a74104041081ff91864b1f2546bbd@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/rb4ee49ecc4c59620ffd5e66e84a17e526c2c3cfa95d0cd682d90d338@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/rb820f1a2a02bf07414be12c653c2ab5321fd87b9bf6c5e635c53ff4b@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52@%3Cnotifications.ofbiz.apache.org%3E
  • lists.apache.org/thread.html/ref0339792ac6dac1dba83c071a727ad72380899bde60f6aaad4031b9@%3Cnotifications.ofbiz.apache.org%3E
  • lists.debian.org/debian-lts-announce/2020/07/msg00010.html
  • nvd.nist.gov/vuln/detail/CVE-2020-11996
  • security.netapp.com/advisory/ntap-20200709-0002
  • tomcat.apache.org/security-10.html
  • tomcat.apache.org/security-8.html
  • tomcat.apache.org/security-9.html
  • usn.ubuntu.com/4596-1
  • www.debian.org/security/2020/dsa-4727
  • www.oracle.com/security-alerts/cpujan2021.html
  • www.oracle.com/security-alerts/cpuoct2020.html

Code Behaviors & Features

Detect and mitigate CVE-2020-11996 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →

Affected versions

All versions starting from 8.5.0 before 8.5.55, all versions starting from 9.0.0-M.1 before 9.0.35, all versions starting from 10.0.0-M1 before 10.0.0-M5

Fixed versions

  • 8.5.55
  • 9.0.35
  • 10.0.0-M5

Solution

Upgrade to versions 8.5.55, 9.0.35, 10.0.0-M5 or above.

Impact 7.5 HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Learn more about CVSS

Weakness

  • CWE-400: Uncontrolled Resource Consumption

Source file

maven/org.apache.tomcat.embed/tomcat-embed-core/CVE-2020-11996.yml

Spotted a mistake? Edit the file on GitLab.

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