Description
Apache HTTP Server versions 2.4.20 to 2.4.43 When trace/debug was enabled for the HTTP/2 module and on certain traffic edge patterns, logging statements were made on the wrong connection, causing concurrent use of memory pools. Configuring the LogLevel of mod_http2 above "info" will mitigate this vulnerability for unpatched servers.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | Apache HTTP Server | 2.4.20 to 2.4.43 | — |
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 | apache2 | 2.4.46-1 | — |
| Debian 13 | apache2 | 2.4.46-1 | — |
| Debian 12 | apache2 | 2.4.46-1 | — |
| Debian 10 | apache2 | 2.4.38-3+deb10u4 | DSA-4757-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | apache2 | 2.4.41-4ubuntu3.1 | USN-4458-1 |
| Ubuntu 18.04 LTS | apache2 | 2.4.29-1ubuntu4.14 | USN-4458-1 |
| Ubuntu 16.04 LTS | apache2 | 2.4.18-2ubuntu3.17 | USN-4458-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | httpd +6 | 2.4.37-39.module+el8.4.0+9658+b87b2deb | RHSA-2021:1809 |
| RHEL 8 | mod_http2 | 1.15.7-3.module+el8.4.0+8625+d397f3da | RHSA-2021:1809 |
| RHEL 8 | mod_md | 1:2.0.8-8.module+el8.3.0+6814+67d1e611 | RHSA-2021:1809 |
| RHEL 8 | mod_ssl +1 | 1:2.4.37-39.module+el8.4.0+9658+b87b2deb | RHSA-2021:1809 |
| RHEL 3 | httpd24-httpd +5 | 2.4.34-22.el7 | RHBA-2020:5280 |
| RHEL 3 | httpd24-mod_ssl +1 | 1:2.4.34-22.el7 | RHBA-2020:5280 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat JBoss Core Services 1 | jbcs-httpd24-apr +1 | 1.6.3-104.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-apr-util +8 | 1.6.1-75.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-brotli +1 | 1.0.6-38.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-curl +2 | 7.64.1-44.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-httpd +6 | 2.4.37-64.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-jansson +1 | 2.11-53.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_cluster-native | 1.3.14-11.Final_redhat_2.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_http2 | 1.15.7-11.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_jk +2 | 1.2.48-10.redhat_1.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_md | 1:2.0.8-30.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_security | 2.9.2-57.GA.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_ssl +1 | 1:2.4.37-64.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-nghttp2 +1 | 1.39.2-34.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl +4 | 1:1.1.1c-32.jbcs.el6 | RHSA-2020:4384 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-chil | 1.0.0-1.jbcs.el7 | RHSA-2020:4384 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 8 | mod_http2 | 1.15.7-3.module_el8.5.0+2609+b30d9eec | ALSA-2021:1809 |
| AlmaLinux 8 | mod_md | 1:2.0.8-8.module_el8.5.0+2609+b30d9eec | ALSA-2021:1809 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | httpd | 2.4.37-39.module+el8.4.0+571+fd70afb1 | RLSA-2021:1809 |
| Rocky Linux 8 | mod_http2 | 1.15.7-3.module+el8.4.0+553+7a69454b | RLSA-2021:1809 |
| Rocky Linux 8 | mod_md | 1:2.0.8-8.module+el8.4.0+553+7a69454b | RLSA-2021:1809 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | apache2 | 2.4.43-3.5.1 | SUSE-SU-2020:2311-1 |
| SLES 15 SP1 | apache2 | 2.4.33-3.33.1 | SUSE-SU-2020:3067-1, SUSE-SU-2020:2344-1 |
| SLES 15 | apache2 | 2.4.33-3.33.1 | SUSE-SU-2020:3067-1, SUSE-SU-2020:2344-1 |
| SLES 12 SP5 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLES 12 SP4 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLES 12 SP2 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLES for SAP 15 | apache2 | 2.4.33-3.33.1 | SUSE-SU-2020:3067-1, SUSE-SU-2020:2344-1 |
| SLES for SAP 12 SP5 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLES for SAP 12 SP4 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLES for SAP 12 SP3 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLES for SAP 12 SP2 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SLE HPC 15 | apache2 | 2.4.33-3.33.1 | SUSE-SU-2020:3067-1, SUSE-SU-2020:2344-1 |
| SUSE OpenStack Cloud Crowbar 9 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SUSE OpenStack Cloud Crowbar 8 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SUSE OpenStack Cloud 9 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SUSE OpenStack Cloud 8 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SUSE OpenStack Cloud 7 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SUSE HPE Helion OpenStack 8 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
| SUSE Enterprise Storage 5 | apache2 | 2.4.23-29.63.1 | SUSE-SU-2020:2450-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.2 | apache2 | 2.4.43-lp152.2.3.1 | openSUSE-SU-2020:1285-1 |
| openSUSE Leap 15.1 | apache2 | 2.4.33-lp151.8.15.1 | openSUSE-SU-2020:1792-1, openSUSE-SU-2020:1293-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | apache2 | 2.4.46-r0 | — |
| Alpine v3.23 | apache2 | 2.4.46-r0 | — |
| Alpine v3.22 | apache2 | 2.4.46-r0 | — |
| Alpine v3.21 | apache2 | 2.4.46-r0 | — |
| Alpine v3.20 | apache2 | 2.4.46-r0 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | apache2 | 2.4.46-r0 | — |
| Alpine v3.18 | apache2 | 2.4.46-r0 | — |
| Alpine v3.17 | apache2 | 2.4.46-r0 | — |
| Alpine v3.16 | apache2 | 2.4.46-r0 | — |
| Alpine v3.15 | apache2 | 2.4.46-r0 | — |
| Alpine v3.14 | apache2 | 2.4.46-r0 | — |
| Alpine v3.13 | apache2 | 2.4.46-r0 | — |
| Alpine v3.12 | apache2 | 2.4.46-r0 | — |
| Alpine v3.11 | apache2 | 2.4.46-r0 | — |
| Alpine v3.10 | apache2 | 2.4.46-r0 | — |
| Alpine v3.9 | apache2 | 2.4.46-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | httpd +7 | 2.4.46-1.amzn2 | ALAS2-2020-1490 |
| Amazon Linux 2 | mod_http2 | 1.15.14-2.amzn2 | ALAS2-2020-1493 |
| Amazon Linux 2 | mod_ssl +1 | 1:2.4.46-1.amzn2 | ALAS2-2020-1490 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | httpd +6 | 2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb | ELSA-2021-1809 |
| Oracle Linux 8 | mod_http2 | 1.15.7-3.module+el8.4.0+20024+b87b2deb | ELSA-2021-1809 |
| Oracle Linux 8 | mod_md | 1:2.0.8-8.module+el8.3.0+7816+49791cfd | ELSA-2021-1809 |
| Oracle Linux 8 | mod_ssl +1 | 1:2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb | ELSA-2021-1809 |
Advisories 21
- ALSA-2021:1809 Moderate: httpd:2.4 security, bug fix, and enhancement update AlmaLinux Security Advisories · Nov 2, 2026
- RHSA-2020:4384 Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.37 SP5 security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2021:1809 Red Hat Security Advisory: httpd:2.4 security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- RHBA-2020:5280 Red Hat Bug Fix Advisory: httpd24 bug fix and enhancement update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- USN-4458-1 apache2 vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-4757-1 apache2 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2021:1809 Moderate: httpd:2.4 security, bug fix, and enhancement update Rocky Linux Security Advisories · Feb 5, 2026
- SUSE-SU-2020:2311-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1285-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2344-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2450-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1293-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1792-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3067-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-0063 Juniper Junos Space: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 8, 2025
- WID-SEC-2024-1591 Juniper JUNOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2024
- WID-SEC-2024-3319 Apache HTTP Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 31, 2024
- WID-SEC-2023-1048 Oracle Construction and Engineering: Mehrere Schwachstellen BSI CERT-Bund (WID) · Feb 4, 2024
- ELSA-2021-1809 Moderate: httpd:2.4 security, bug fix, and enhancement update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 25, 2021
- ALAS2-2020-1493 Important: mod_http2 security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 16, 2020
- ALAS2-2020-1490 Important: httpd security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 16, 2020
References
- https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2020-11993
- GLSA-202008-04 vendor-advisory
- [httpd-dev] 20200808 Security announcements for CVE-2020-9490/CVE-2020-11993 ? mailing-list
- [httpd-dev] 20200811 Which version fixed the CVE-2020-9490, CVE-2020-11984 and CVE-2020-11993 vulnerabilities? mailing-list
- [httpd-dev] 20200811 Re: Which version fixed the CVE-2020-9490, CVE-2020-11984 and CVE-2020-11993 vulnerabilities? mailing-list
- USN-4458-1 vendor-advisory
- FEDORA-2020-8122a8daa2 vendor-advisory
- FEDORA-2020-b58dc5df38 vendor-advisory
- openSUSE-SU-2020:1285 vendor-advisory
- openSUSE-SU-2020:1293 vendor-advisory
- DSA-4757 vendor-advisory
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://security.netapp.com/advisory/ntap-20200814-0005/
- openSUSE-SU-2020:1792 vendor-advisory
- https://www.oracle.com/security-alerts/cpujan2021.html
- http://packetstormsecurity.com/files/160393/Apache-2-HTTP2-Module-Concurrent-Pool-Usage.html
- [httpd-cvs] 20210330 svn commit: r1073139 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073143 [3/3] - in /websites/staging/httpd/trunk/content: ./ security/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1888194 [13/13] - /httpd/site/trunk/content/security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073140 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.ht mailing-list
- [httpd-cvs] 20210330 svn commit: r1073139 [13/13] - in /websites/staging/httpd/trunk/content: ./ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073149 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073149 [13/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073171 - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-11984.json security/json/CVE-2020-11993.json security/vulnerabilities_24.html mailing-list
- [httpd-cvs] 20210330 svn commit: r1888228 - in /httpd/site/trunk/content/security/json: CVE-2020-11984.json CVE-2020-11993.json mailing-list
- [httpd-cvs] 20210606 svn commit: r1075470 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-13938.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabiliti mailing-list