Description
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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache | Apache Tomcat | 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35, 8.5.0 to 8.5.55 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | tomcat9 | 9.0.36-1 | — |
| Debian 13 | tomcat9 | 9.0.36-1 | — |
| Debian 12 | tomcat9 | 9.0.36-1 | — |
| Debian 10 | tomcat9 | 9.0.31-1~deb10u2 | DSA-4727-1 |
| Debian 9 | tomcat8 | 8.5.54-0+deb9u2 | DLA-2279-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | tomcat9 | 9.0.31-1ubuntu0.1 | USN-4596-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | tomcat8 +1 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat JBoss Web Server 5 | jws5-jboss-logging | 3.4.1-1.Final_redhat_00001.1.el6jws | RHSA-2020:5170 |
| Red Hat JBoss Web Server 5 | jws5-mod_cluster +1 | 1.4.2-7.Final_redhat_00002.2.el6jws | RHSA-2020:5170 |
| Red Hat JBoss Web Server 5 | jws5-tomcat +9 | 9.0.36-6.redhat_5.2.el6jws | RHSA-2020:5170 |
| Red Hat JBoss Web Server 5 | jws5-tomcat-native | 1.2.25-2.redhat_2.el6jws | RHSA-2020:5170 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | tomcat | 9.0.36-3.3.1 | SUSE-SU-2020:1983-1 |
| SLES 15 SP1 | tomcat | 9.0.36-4.38.1 | SUSE-SU-2020:1962-1 |
| SLES 15 | tomcat | 9.0.36-3.60.1 | SUSE-SU-2020:1841-1 |
| SLES 12 SP5 | tomcat | 9.0.36-3.42.2 | SUSE-SU-2020:1963-1 |
| SLES 12 SP4 | tomcat | 9.0.36-3.42.2 | SUSE-SU-2020:1963-1 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 | tomcat | 9.0.36-3.60.1 | SUSE-SU-2020:1841-1 |
| SLES for SAP 12 SP5 | tomcat | 9.0.36-3.42.2 | SUSE-SU-2020:1963-1 |
| SLES for SAP 12 SP4 | tomcat | 9.0.36-3.42.2 | SUSE-SU-2020:1963-1 |
| SLE HPC 15 | tomcat | 9.0.36-3.60.1 | SUSE-SU-2020:1841-1 |
| SUSE OpenStack Cloud Crowbar 9 | tomcat | 9.0.36-3.42.2 | SUSE-SU-2020:1963-1 |
| SUSE OpenStack Cloud 9 | tomcat | 9.0.36-3.42.2 | SUSE-SU-2020:1963-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | tomcat | 9.0.36-8.4 | openSUSE-SU-2024:11468-1 |
| openSUSE Tumbleweed | tomcat10 | 10.1.14-1.1 | openSUSE-SU-2024:13441-1 |
| openSUSE Leap 15.2 | tomcat | 9.0.36-lp152.2.3.1 | openSUSE-SU-2020:1063-1 |
| openSUSE Leap 15.1 | tomcat | 9.0.36-lp151.3.24.1 | openSUSE-SU-2020:1051-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
rusakovichma/tomcat-embed-core-9.0.31-CVE-2020-11996 ★ 5 · Jul 27, 2020
tomcat-embed-core-9.0.31 CVE-2020-11996 Test PoC
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Maven | org.apache.tomcat:tomcat | >= 10.0.0-M1, < 10.0.0-M5 | 10.0.0-M5 | GHSA-53hp-jpwq-2jgq |
| Maven | org.apache.tomcat:tomcat | >= 9.0.0.M1, < 9.0.35 | 9.0.35 | GHSA-53hp-jpwq-2jgq |
| Maven | org.apache.tomcat:tomcat | >= 8.5.0, < 8.5.55 | 8.5.55 | GHSA-53hp-jpwq-2jgq |
| Maven | org.apache.tomcat.embed:tomcat-embed-core | >= 10.0.0-M1, < 10.0.0-M5 | 10.0.0-M5 | GHSA-53hp-jpwq-2jgq |
| Maven | org.apache.tomcat.embed:tomcat-embed-core | >= 9.0.0.M1, < 9.0.35 | 9.0.35 | GHSA-53hp-jpwq-2jgq |
| Maven | org.apache.tomcat.embed:tomcat-embed-core | >= 8.5.0, < 8.5.55 | 8.5.55 | GHSA-53hp-jpwq-2jgq |
Advisories 16
- RHSA-2020:5170 Red Hat Security Advisory: Red Hat JBoss Web Server 5.4 security release Red Hat Security Advisories (RHSA) · Aug 5, 2026
- USN-4596-1 tomcat9 vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-4727-1 tomcat9 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2279-1 tomcat8 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2020:1841-1 Security update for tomcat SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:1963-1 Security update for tomcat SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11468-1 tomcat-9.0.36-8.4 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:1983-1 Security update for tomcat SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:13441-1 tomcat10-10.1.14-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1063-1 Security update for tomcat SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:1962-1 Security update for tomcat SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2026-0205 Oracle MySQL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 25, 2026
- WID-SEC-2022-1375 JFrog Artifactory: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 12, 2025
- openSUSE-SU-2020:1051-1 Security update for tomcat SUSE / openSUSE Security Updates · May 7, 2025
- NCSC-2025-0123 Kwetsbaarheden verholpen in Oracle Database Producten NCSC-NL (Netherlands) · Apr 16, 2025
- WID-SEC-2024-0528 Dell Data Protection Advisor: Mehrere Schwachstellen BSI CERT-Bund (WID) · Feb 29, 2024
References
- https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E
- [ofbiz-notifications] 20200628 [jira] [Updated] (OFBIZ-11847) CLONE - Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200628 [jira] [Closed] (OFBIZ-11847) CLONE - Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200628 [jira] [Created] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200628 [jira] [Created] (OFBIZ-11847) CLONE - Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-commits] 20200628 [ofbiz-framework] branch release18.12 updated: Fixed: Upgrades Tomcat to 9.0.36 due to CVE-2020-11996 (OFBIZ-11848) mailing-list
- [ofbiz-notifications] 20200628 [jira] [Closed] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200628 [jira] [Commented] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-commits] 20200628 [ofbiz-framework] branch release17.12 updated: Fixed: Upgrades Tomcat to 9.0.36 due to CVE-2020-11996 (OFBIZ-11848) mailing-list
- [ofbiz-commits] 20200628 [ofbiz-framework] branch trunk updated: Fixed: Upgrades Tomcat to 9.0.36 due to CVE-2020-11996 (OFBIZ-11848) mailing-list
- [ofbiz-notifications] 20200701 [jira] [Reopened] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200703 [jira] [Comment Edited] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200703 [jira] [Closed] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [ofbiz-notifications] 20200703 [jira] [Commented] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list
- [debian-lts-announce] 20200712 [SECURITY] [DLA 2279-1] tomcat8 security update mailing-list
- DSA-4727 vendor-advisory
- openSUSE-SU-2020:1051 vendor-advisory
- openSUSE-SU-2020:1063 vendor-advisory
- [tomcat-users] 20201008 Is Tomcat7 supports HTTP2 mailing-list
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://security.netapp.com/advisory/ntap-20200709-0002/
- USN-4596-1 vendor-advisory
- https://www.oracle.com/security-alerts/cpujan2021.html
- [ofbiz-notifications] 20210301 [jira] [Updated] (OFBIZ-11848) Upgrade Tomcat from 9.0.34 to 9.0.36 (CVE-2020-11996) mailing-list