Description
In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a heap overflow
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache Software Foundation | Apache HTTP Server | 2.4.46, 2.4.43, 2.4.41, 2.4.39, 2.4.38, 2.4.37, 2.4.35, 2.4.34, 2.4.33, 2.4.29, 2.4.28, 2.4.27, 2.4.26, 2.4.25, 2.4.23, 2.4.20, 2.4.18, 2.4.17, 2.4.16, 2.4.12, 2.4.10, 2.4.9, 2.4.7, 2.4.6, 2.4.4, 2.4.3, 2.4.2, 2.4.1, 2.4.0 | — |
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 | 2.4.46-6 | — |
| Debian 13 | apache2 | 2.4.46-6 | — |
| Debian 12 | apache2 | 2.4.46-6 | — |
| Debian 10 | apache2 | 2.4.38-3+deb10u5 | DSA-4937-1 |
| Debian 9 | apache2 | 2.4.25-3+deb9u10 | DLA-2706-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | apache2 | 2.4.41-4ubuntu3.3 | USN-4994-1 |
| Ubuntu 18.04 LTS | apache2 | 2.4.29-1ubuntu4.16 | USN-4994-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | apache2 | 2.4.18-2ubuntu3.17+esm1 | USN-4994-2 |
| Ubuntu Pro 14.04 LTS | apache2 | 2.4.7-1ubuntu4.22+esm1 | USN-4994-2 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | httpd +6 | 2.4.37-39.module+el8.4.0+12865+a7065a39.1 | RHSA-2021:3816 |
| RHEL 8 | mod_http2 | 1.15.7-3.module+el8.4.0+8625+d397f3da | RHSA-2021:3816 |
| RHEL 8 | mod_md | 1:2.0.8-8.module+el8.3.0+6814+67d1e611 | RHSA-2021:3816 |
| RHEL 8 | mod_ssl +1 | 1:2.4.37-39.module+el8.4.0+12865+a7065a39.1 | RHSA-2021:3816 |
| RHEL 7 | httpd +5 | 2.4.6-97.el7_9.4 | RHSA-2022:0143 |
| RHEL 7 | mod_ssl +1 | 1:2.4.6-97.el7_9.4 | RHSA-2022:0143 |
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 | 1.6.3-107.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-apr-util +8 | 1.6.1-84.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-curl +2 | 7.78.0-2.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-httpd +6 | 2.4.37-78.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_cluster-native | 1.3.16-9.Final_redhat_2.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_http2 | 1.15.7-21.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_jk +2 | 1.2.48-20.redhat_1.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_md | 1:2.0.8-40.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_security | 2.9.2-67.GA.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_ssl +1 | 1:2.4.37-78.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-nghttp2 +1 | 1.39.2-39.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl +4 | 1:1.1.1g-8.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-chil | 1.0.0-7.el8jbcs | RHSA-2021:4614 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-pkcs11 | 0.4.10-22.el8jbcs | RHSA-2021:4614 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 8 | httpd +6 | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux 8 | mod_http2 | 1.15.7-3.module_el8.5.0+2609+b30d9eec | ALSA-2021:4537, ALSA-2021:3816 |
| AlmaLinux 8 | mod_md | 1:2.0.8-8.module_el8.5.0+2609+b30d9eec | ALSA-2021:4537, ALSA-2021:3816 |
| AlmaLinux 8 | mod_ssl +1 | 1:2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | httpd | 2.4.37-39.module+el8.4.0+571+fd70afb1 | RLSA-2021:3816 |
| Rocky Linux 8 | mod_http2 | 1.15.7-3.module+el8.4.0+553+7a69454b | RLSA-2021:3816 |
| Rocky Linux 8 | mod_md | 1:2.0.8-8.module+el8.4.0+553+7a69454b | RLSA-2021:3816 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP3 | apache2 | 2.4.43-3.22.1 | SUSE-SU-2021:2127-1 |
| SLES 15 SP2 | apache2 | 2.4.43-3.22.1 | SUSE-SU-2021:2127-1 |
| SLES 15 SP1 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SLES 15 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SLES 12 SP5 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
Show 19 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP4 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SLES 12 SP3 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SLES 12 SP2 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SLES for SAP 15 SP1 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SLES for SAP 15 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SLES for SAP 12 SP5 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SLES for SAP 12 SP4 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SLES for SAP 12 SP3 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SLE HPC 15 SP1 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SLE HPC 15 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SUSE OpenStack Cloud Crowbar 9 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SUSE OpenStack Cloud Crowbar 8 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SUSE OpenStack Cloud 9 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SUSE OpenStack Cloud 8 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SUSE Manager Server 4.0 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SUSE Manager Retail Branch Server 4.0 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SUSE Manager Proxy 4.0 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
| SUSE HPE Helion OpenStack 8 | apache2 | 2.4.23-29.74.1 | SUSE-SU-2021:2006-1 |
| SUSE Enterprise Storage 6 | apache2 | 2.4.33-3.50.1 | SUSE-SU-2021:2004-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.3 | apache2 | 2.4.43-3.22.1 | openSUSE-SU-2021:2127-1 |
| openSUSE Leap 15.2 | apache2 | 2.4.43-lp152.2.15.1 | openSUSE-SU-2021:0908-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | apache2 | 2.4.48-r0 | — |
| Alpine v3.23 | apache2 | 2.4.48-r0 | — |
| Alpine v3.22 | apache2 | 2.4.48-r0 | — |
| Alpine v3.21 | apache2 | 2.4.48-r0 | — |
| Alpine v3.20 | apache2 | 2.4.48-r0 | — |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | apache2 | 2.4.48-r0 | — |
| Alpine v3.18 | apache2 | 2.4.48-r0 | — |
| Alpine v3.17 | apache2 | 2.4.48-r0 | — |
| Alpine v3.16 | apache2 | 2.4.48-r0 | — |
| Alpine v3.15 | apache2 | 2.4.48-r0 | — |
| Alpine v3.14 | apache2 | 2.4.48-r0 | — |
| Alpine v3.13 | apache2 | 2.4.48-r0 | — |
| Alpine v3.12 | apache2 | 2.4.48-r0 | — |
| Alpine v3.11 | apache2 | 2.4.48-r0 | — |
| Alpine v3.10 | apache2 | 2.4.48-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | httpd +7 | 2.4.48-2.amzn2 | ALAS2-2021-1674 |
| Amazon Linux 2 | mod_ssl +1 | 1:2.4.48-2.amzn2 | ALAS2-2021-1674 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | httpd | 2.4.46-10 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | httpd +6 | 2.4.37-39.0.1.module+el8.4.0+20372+b87b2deb.1 | ELSA-2021-3816 |
| Oracle Linux 8 | mod_http2 | 1.15.7-3.module+el8.4.0+20024+b87b2deb | ELSA-2021-3816 |
| Oracle Linux 8 | mod_md | 1:2.0.8-8.module+el8.3.0+7816+49791cfd | ELSA-2021-3816 |
| Oracle Linux 8 | mod_ssl +1 | 1:2.4.37-39.0.1.module+el8.4.0+20372+b87b2deb.1 | ELSA-2021-3816 |
| Oracle Linux 7 | httpd +5 | 2.4.6-97.0.5.el7_9.4 | ELSA-2022-0143 |
| Oracle Linux 7 | mod_ssl +1 | 1:2.4.6-97.0.5.el7_9.4 | ELSA-2022-0143 |
Advisories 22
- ALSA-2021:4537 Important: httpd:2.4 security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2021:3816 Important: httpd:2.4 security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2022:0143 Red Hat Security Advisory: httpd security update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:4614 Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.37 SP10 security update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:3816 Red Hat Security Advisory: httpd:2.4 security update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- USN-4994-2 apache2 vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
- USN-4994-1 apache2 vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-4937-1 apache2 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2706-1 apache2 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2021:3816 Important: httpd:2.4 security update Rocky Linux Security Advisories · Feb 4, 2026
- SUSE-SU-2021:2004-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:0908-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2127-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:2127-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2006-1 Security update for apache2 SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2024-0064 Juniper Produkte: Mehrere Schwachstellen BSI CERT-Bund (WID) · Apr 10, 2025
- WID-SEC-2024-1591 Juniper JUNOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2024
- WID-SEC-2022-0438 Apache HTTP Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 26, 2024
- ICSA-22-132-02 Mitsubishi Electric MELSOFT iQ AppPortal CISA ICS & IT advisories · May 12, 2022
- ELSA-2022-0143 Important: httpd security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jan 18, 2022
- ELSA-2021-3816 Important: httpd:2.4 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 13, 2021
- ALAS2-2021-1674 Moderate: httpd security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jul 1, 2021
References
- http://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E
- [httpd-announce] 20210609 CVE-2021-26691: mod_session response handling heap overflow mailing-list
- [httpd-dev] 20210610 Re: svn commit: r1890598 - in /httpd/site/trunk/content/security/json: CVE-2019-17567.json CVE-2020-13938.json CVE-2020-13950.json CVE-2020-35452.json CVE-2021-26690.json CVE-2021-26691.json CVE-2021-30641.json CVE-2021-31618.jso mailing-list
- [oss-security] 20210609 CVE-2021-26691: Apache httpd: mod_session response handling heap overflow mailing-list
- [debian-lts-announce] 20210709 [SECURITY] [DLA 2706-1] apache2 security update mailing-list
- DSA-4937 vendor-advisory
- GLSA-202107-38 vendor-advisory
- FEDORA-2021-dce7e7738e vendor-advisory
- FEDORA-2021-e3f6dd670d vendor-advisory
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://security.netapp.com/advisory/ntap-20210702-0001/
- https://www.oracle.com/security-alerts/cpujan2022.html