CVE-2021-26690 in the critical feed json
mod_session NULL pointer dereference
published 2021-06-10 5 y ago modified 2026-09-08 2 mo ago also BIT-apache-2021-26690 , EUVD-2021-13483
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 65.1%
- EPSS 65.1% chance of exploitation in 30 days, percentile 99.2%
- public exploits
- 0
- none known
Summary
Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service
Patch / fix
- bitnami apache 2.4.47
- apache2 Debian 14, Debian 13, Debian 12 2.4.46-6
debian advisories DEBIAN-CVE-2021-26690
- apache2 Ubuntu 18.04 LTS 2.4.29-1ubuntu4.16
- apache2 Ubuntu 20.04 LTS 2.4.41-4ubuntu3.3
- apache2 Ubuntu Pro 14.04 LTS 2.4.7-1ubuntu4.22+esm1
- apache2 Ubuntu Pro 16.04 LTS 2.4.18-2ubuntu3.17+esm1
ubuntu advisories UBUNTU-CVE-2021-26690
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
- jbcs-httpd24-apr jboss core services 1 1.6.3-107.jbcs.el7
- jbcs-httpd24-apr jboss core services 1 1.6.3-107.el8jbcs
- jbcs-httpd24-curl jboss core services 1 7.78.0-2.jbcs.el7
- jbcs-httpd24-curl jboss core services 1 7.78.0-2.el8jbcs
- jbcs-httpd24-httpd jboss core services 1 2.4.37-78.jbcs.el7
- jbcs-httpd24-httpd jboss core services 1 2.4.37-78.el8jbcs
- jbcs-httpd24-mod_jk jboss core services 1 1.2.48-20.redhat_1.jbcs.el7
- jbcs-httpd24-mod_jk jboss core services 1 1.2.48-20.redhat_1.el8jbcs
red hat advisories RHSA-2021:4614RHSA-2021:4257
- apache2 SLE Module for Server Applications 15 SP3, SLE Module for Server Applications 15 SP2, SLE Module for Package Hub 15 SP3 +2 more 2.4.43-3.22.1
- apache2 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 2.4.23-29.74.1
- apache2 SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +10 more 2.4.33-3.50.1
suse advisories SUSE-SU-2021:2127-1SUSE-SU-2021:2006-1SUSE-SU-2021:2004-1
- apache2 openSUSE Leap 15.3 2.4.43-3.22.1
- apache2 openSUSE Leap 15.2 2.4.43-lp152.2.15.1
opensuse advisories openSUSE-SU-2021:2127-1openSUSE-SU-2021:0908-1
- mod_md AlmaLinux 8 1:2.0.8-8.module_el8.5.0+2609+b30d9eec
- mod_md AlmaLinux 8 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
- mod_http2 AlmaLinux 8 1.15.7-3.module_el8.5.0+2609+b30d9eec
almalinux advisories ALSA-2021:4257
- httpd Rocky Linux 8 2.4.37-41.module+el8.5.0+695+1fa8055e
- mod_md Rocky Linux 8 1:2.0.8-8.module+el8.5.0+695+1fa8055e
- mod_md Rocky Linux 8 1:2.0.8-8.module+el8.4.0+553+7a69454b
- mod_http2 Rocky Linux 8 1.15.7-3.module+el8.4.0+553+7a69454b
- mod_http2 Rocky Linux 8 1.15.7-3.module+el8.5.0+695+1fa8055e
rocky linux advisories RLSA-2021:4257
- apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 2.4.48-r0
alpine advisories ALPINE-CVE-2021-26690
Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- httpd CBL-Mariner 2.0 2.4.46-10
azure linux advisories AZL-6476
Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT
- apache Arch Linux 2.4.47-1
arch linux advisories AVG-2053
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-2021-26690 updated cvss 7.5
httpd: mod_session: NULL pointer dereference when parsing Cookie header
-
Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more Red Hat JBoss Enterprise Application Platform 6 httpd22 httpd22 Red Hat JBoss Enterprise Web Server 2 httpd22 httpd22affected: workaround, no fix planned “Out of support scope”
-
Red Hat Software Collections httpd24-httpd, httpd24-mod_md, httpd24-mod_ssl, httpd24-mod_ldap, httpd24-httpd-tools, httpd24-mod_session, +2 moreaffected: workaround, no fix planned “Will not fix”
-
Red Hat Enterprise Linux AppStream (v. 8) mod_md 2.0.8-8.module+el8.3.0+6814+67d1e611, httpd 2.4.37-41.module+el8.5.0+11772+c8e0c271, mod_http2 1.15.7-3.module+el8.4.0+8625+d397f3da, mod_ssl 2.4.37-41.module+el8.5.0+11772+c8e0c271, mod_ldap 2.4.37-41.module+el8.5.0+11772+c8e0c271, httpd-tools 2.4.37-41.module+el8.5.0+11772+c8e0c271, +4 morefixed: vendor fix RHSA-2021:4257
-
Red Hat JBoss Core Servicesfixed: vendor fix RHSA-2021:4613
-
Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-apr 1.6.3-107.jbcs.el7, jbcs-httpd24-curl 7.78.0-2.jbcs.el7, jbcs-httpd24-httpd 2.4.37-78.jbcs.el7, jbcs-httpd24-mod_md 2.0.8-40.jbcs.el7, jbcs-httpd24-libcurl 7.78.0-2.jbcs.el7, jbcs-httpd24-openssl 1.1.1g-8.jbcs.el7, +26 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-apr 1.6.3-107.el8jbcs, jbcs-httpd24-curl 7.78.0-2.el8jbcs, jbcs-httpd24-httpd 2.4.37-78.el8jbcs, jbcs-httpd24-mod_md 2.0.8-40.el8jbcs, jbcs-httpd24-libcurl 7.78.0-2.el8jbcs, jbcs-httpd24-openssl 1.1.1g-8.el8jbcs, +26 morefixed: vendor fix RHSA-2021:4614
-
Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 9 httpd, mod_lua, mod_ssl, mod_ldap, httpd-core, httpd-tools, +4 morenot 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
Exploit prediction
65.07% chance of exploitation in the next 30 days, higher than 99.2% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| 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 |
|---|---|---|---|
| bitnami | apache | >=2.4.0, <2.4.47 |
2.4.47 |
Affected products
- Apache Software Foundation Apache HTTP Server
Classification
- Weakness
-
- CWE-476 NULL Pointer Dereference
- Technology feeds
References
-
debian.org
/security/2021/dsa-4937
vendor-advisory, mailing-list, third-party-advisory, advisory
-
security.gentoo.org
/glsa/202107-38
vendor-advisory, third-party-advisory, advisory
-
lists.fedoraproject.org
/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/
vendor-advisory, web
-
lists.fedoraproject.org
/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/
vendor-advisory, web
-
httpd.apache.org
/security/vulnerabilities_24.html
release-notes, vendor-advisory, advisory
-
lists.apache.org
/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E
mailing-list, vendor-advisory, advisory
-
lists.apache.org
/thread.html/rae406c1d19c0dfd3103c96923dadac2af1cd0bad6905ab1ede153865%40%3Cannounce.httpd.apache.org%3E
mailing-list, web
-
lists.apache.org
/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E
mailing-list, web
-
openwall.com
/lists/oss-security/2021/06/10/6
mailing-list, third-party-advisory, advisory
-
lists.debian.org
/debian-lts-announce/2021/07/msg00006.html
mailing-list, third-party-advisory, advisory
-
oracle.com
/security-alerts/cpuoct2021.html
third-party-advisory, advisory
-
security.netapp.com
/advisory/ntap-20210702-0001/
third-party-advisory, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-26690
web
Sources
- CVE List CVE-2021-26690
- NVD CVE-2021-26690
- OSV BIT-apache-2021-26690
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.