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Fencer Vulns
high 7.5

CVE-2020-11996 in the critical feed json

Uncontrolled Resource Consumption in Apache Tomcat

published 2020-06-26 6 y ago modified 2026-10-08 31 d ago also BIT-tomcat-2020-11996 , EUVD-2022-0828 , GHSA-53hp-jpwq-2jgq

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
26.7%
EPSS 26.7% chance of exploitation in 30 days, percentile 98%
public exploits
0
none known

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 concurrent HTTP/2 connections, the server could become unresponsive.

Patch / fix

  • maven org.apache.tomcat:tomcat 8.5.55, 9.0.35, 10.0.0-M5
  • maven org.apache.tomcat.embed:tomcat-embed-core 8.5.55, 9.0.35, 10.0.0-M5
  • bitnami tomcat 8.5.56, 9.0.36
  • tomcat9 Debian 14, Debian 13, Debian 12 9.0.36-1

debian advisories DEBIAN-CVE-2020-11996

  • tomcat9 Ubuntu 20.04 LTS 9.0.31-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2020-11996

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jws5-tomcat jboss enterprise web server 5.4 9.0.36-6.redhat_5.2.el6jws
  • jws5-tomcat jboss enterprise web server 5.4 9.0.36-6.redhat_5.2.el7jws
  • jws5-tomcat jboss enterprise web server 5.4 9.0.36-6.redhat_5.2.el8jws
  • jws5-tomcat-lib jboss enterprise web server 5.4 9.0.36-6.redhat_5.2.el6jws
  • jws5-tomcat-lib jboss enterprise web server 5.4 9.0.36-6.redhat_5.2.el7jws
  • jws5-tomcat-lib jboss enterprise web server 5.4 9.0.36-6.redhat_5.2.el8jws
  • jws5-mod_cluster jboss enterprise web server 5.4 1.4.2-7.Final_redhat_00002.2.el6jws
  • jws5-mod_cluster jboss enterprise web server 5.4 1.4.2-7.Final_redhat_00002.2.el7jws

red hat advisories RHSA-2020:5170

  • tomcat SLE Module for Web and Scripting 15 SP2 9.0.36-3.3.1
  • tomcat SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES 12 SP5 +3 more 9.0.36-3.42.2
  • tomcat SLE Module for Web and Scripting 15 SP1 9.0.36-4.38.1
  • tomcat SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 9.0.36-3.60.1

suse advisories SUSE-SU-2020:1983-1SUSE-SU-2020:1963-1SUSE-SU-2020:1962-1SUSE-SU-2020:1841-1

  • tomcat openSUSE Tumbleweed 9.0.36-8.4
  • tomcat10 openSUSE Tumbleweed 10.1.14-1.1
  • tomcat openSUSE Leap 15.2 9.0.36-lp152.2.3.1
  • tomcat openSUSE Leap 15.1 9.0.36-lp151.3.24.1

opensuse advisories openSUSE-SU-2024:11468-1openSUSE-SU-2024:13441-1openSUSE-SU-2020:1063-1openSUSE-SU-2020:1051-1

  • tomcat9 Arch Linux 9.0.37-1

arch linux advisories AVG-1196

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-11996 updated cvss 7.5

tomcat: specially crafted sequence of HTTP/2 requests can lead to DoS

  • Red Hat Enterprise Linux 8 pki-servlet-engine, pki-servlet-4.0-api
    affected: no fix planned “Will not fix”
  • Red Hat JBoss Data Grid 6 jbossweb jbossweb Red Hat JBoss Data Virtualization 6 jbossweb jbossweb Red Hat JBoss Enterprise Application Platform 6 jbossweb jbossweb Red Hat JBoss Fuse 6 tomcat Red Hat OpenStack Platform 10 (Newton) opendaylight
    affected: no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 13 (Queens) opendaylight
    affected: no fix planned “Will not fix”
  • Red Hat Fuse 7.9
    fixed: vendor fix RHSA-2021:3140
  • Red Hat JBoss Web Server 5
    fixed: vendor fix RHSA-2020:5173
  • Red Hat JBoss Web Server 5.4 for RHEL 6 Server jws5-tomcat 9.0.36-6.redhat_5.2.el6jws, jws5-tomcat-lib 9.0.36-6.redhat_5.2.el6jws, jws5-tomcat-native 1.2.25-2.redhat_2.el6jws, jws5-tomcat-javadoc 9.0.36-6.redhat_5.2.el6jws, jws5-tomcat-selinux 9.0.36-6.redhat_5.2.el6jws, jws5-tomcat-webapps 9.0.36-6.redhat_5.2.el6jws, +8 more Red Hat JBoss Web Server 5.4 for RHEL 7 Server jws5-tomcat 9.0.36-6.redhat_5.2.el7jws, jws5-tomcat-lib 9.0.36-6.redhat_5.2.el7jws, jws5-tomcat-native 1.2.25-2.redhat_2.el7jws, jws5-tomcat-javadoc 9.0.36-6.redhat_5.2.el7jws, jws5-tomcat-selinux 9.0.36-6.redhat_5.2.el7jws, jws5-tomcat-webapps 9.0.36-6.redhat_5.2.el7jws, +8 more Red Hat JBoss Web Server 5.4 for RHEL 8 jws5-tomcat 9.0.36-6.redhat_5.2.el8jws, jws5-tomcat-lib 9.0.36-6.redhat_5.2.el8jws, jws5-tomcat-native 1.2.25-2.redhat_2.el8jws, jws5-tomcat-javadoc 9.0.36-6.redhat_5.2.el8jws, jws5-tomcat-selinux 9.0.36-6.redhat_5.2.el8jws, jws5-tomcat-webapps 9.0.36-6.redhat_5.2.el8jws, +8 more
    fixed: vendor fix RHSA-2020:5170
  • Red Hat support for Spring Boot 2.3.6
    fixed: vendor fix RHSA-2021:0292
  • Red Hat Text-Only RHOAR
    fixed: vendor fix RHSA-2020:5388
show 1 more
  • Red Hat Decision Manager 7 tomcat Red Hat Enterprise Linux 6 tomcat6, tomcat6-lib, tomcat6-log4j, tomcat6-javadoc, tomcat6-webapps, tomcat6-el-2.1-api, +4 more Red Hat Enterprise Linux 7 tomcat, tomcat-lib, tomcat-jsvc, tomcat-javadoc, tomcat-webapps, tomcat-el-2.2-api, +4 more Red Hat JBoss Web Server 3 tomcat Red Hat Process Automation 7 tomcat
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
31 d ago

Exploit prediction

26.70% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven org.apache.tomcat:tomcat
>=10.0.0-M1, <10.0.0-M5
>=9.0.0.M1, <9.0.35
>=8.5.0, <8.5.55
10.0.0-M5
9.0.35
8.5.55
maven org.apache.tomcat.embed:tomcat-embed-core
>=10.0.0-M1, <10.0.0-M5
>=9.0.0.M1, <9.0.35
>=8.5.0, <8.5.55
10.0.0-M5
9.0.35
8.5.55
bitnami tomcat
>=8.5.0, <8.5.56
>=9.0.0, <9.0.36
8.5.56
9.0.36

Affected products

  • Apache Apache Tomcat

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.