CVE-2021-26690
HighApache 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
Published Jul 12, 2021 · Updated Sep 8, 2026 · Also known as ALPINE-CVE-2021-26690, BIT-apache-2021-26690, DEBIAN-CVE-2021-26690, UBUNTU-CVE-2021-26690
Key Facts
Patch immediately- CVE-2021-26690 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting HTTP Server (Apache), Enterprise Manager Ops Center (Oracle), Instantis Enterprisetrack (Oracle) and 22 more products.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 65% probability of exploitation in the next 30 days.
- Fixed versions are available, including apache 2.4.47, apache 2.4.47-1, HTTP Server <=2.4.46.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
65%
Higher than 99.2% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2021-26690 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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
Affected Products
342 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| HTTP ServerApache | >= 2.4.46 | 2.4.46 |
| Enterprise Manager Ops CenterOracle | 12.4.0.0 | n/a |
| Instantis EnterprisetrackOracle | 17.1, 17.2, 17.3 | n/a |
| Zfs Storage Appliance KitOracle | 8.8 | n/a |
| Debian LinuxDebian | 10.0, 9.0 | n/a |
Patched Releases
apache
2.4.47, 2.4.47-1
HTTP Server
<=2.4.46
apache2
2.4.18-2ubuntu3.17+esm1, 2.4.23-29.74.1, 2.4.25-3+deb9u10, 2.4.29-1ubuntu4.16, 2.4.33-3.50.1, 2.4.38-3+deb10u5, 2.4.41-4ubuntu3.3, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1, 2.4.46-6, 2.4.48-r0, 2.4.7-1ubuntu4.22+esm1
apache2-devel
2.4.23-29.74.1, 2.4.33-3.50.1, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1
apache2-doc
2.4.23-29.74.1, 2.4.33-3.50.1, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1
apache2-event
2.4.43-3.22.1, 2.4.43-lp152.2.15.1
apache2-example-pages
2.4.23-29.74.1, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1
apache2-prefork
2.4.23-29.74.1, 2.4.33-3.50.1, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1
apache2-utils
2.4.23-29.74.1, 2.4.33-3.50.1, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1
apache2-worker
2.4.23-29.74.1, 2.4.33-3.50.1, 2.4.43-3.22.1, 2.4.43-lp152.2.15.1
httpd
2.4.37-39.0.2.module+el8.4.0+20402+038b8ccd.1, 2.4.37-41.0.1.module+el8.5.0+20323+c8e0c271, 2.4.37-41.module+el8.5.0+695+1fa8055e, 2.4.46-10, 2.4.46-5, 2.4.48-1.ph1, 2.4.48-1.ph2, 2.4.48-2.amzn2, 2.4.6-97.0.3.el7_9.1
httpd-devel
2.4.37-39.0.2.module+el8.4.0+20402+038b8ccd.1, 2.4.37-41.0.1.module+el8.5.0+20323+c8e0c271, 2.4.48-2.amzn2, 2.4.6-97.0.3.el7_9.1
httpd-filesystem
2.4.37-39.0.2.module+el8.4.0+20402+038b8ccd.1, 2.4.37-41.0.1.module+el8.5.0+20323+c8e0c271, 2.4.48-2.amzn2
httpd-manual
2.4.37-39.0.2.module+el8.4.0+20402+038b8ccd.1, 2.4.37-41.0.1.module+el8.5.0+20323+c8e0c271, 2.4.48-2.amzn2, 2.4.6-97.0.3.el7_9.1
httpd-tools
2.4.37-39.0.2.module+el8.4.0+20402+038b8ccd.1, 2.4.37-41.0.1.module+el8.5.0+20323+c8e0c271, 2.4.48-2.amzn2, 2.4.6-97.0.3.el7_9.1
httpd:2.4
8050020210712211742.b4937e53
httpd24
2.4.48-1.92.amzn1
httpd24-devel
2.4.48-1.92.amzn1
httpd24-manual
2.4.48-1.92.amzn1
httpd24-tools
2.4.48-1.92.amzn1
jbcs-httpd24-apr
0:1.6.3-107.el8jbcs, 0:1.6.3-107.jbcs.el7
jbcs-httpd24-apr-util
0:1.6.1-84.el8jbcs, 0:1.6.1-84.jbcs.el7
jbcs-httpd24-curl
0:7.78.0-2.el8jbcs, 0:7.78.0-2.jbcs.el7
jbcs-httpd24-httpd
0:2.4.37-78.el8jbcs, 0:2.4.37-78.jbcs.el7
jbcs-httpd24-mod_cluster-native
0:1.3.16-9.Final_redhat_2.el8jbcs, 0:1.3.16-9.Final_redhat_2.jbcs.el7
Timeline
Publicly disclosed
Jul 12, 2021
Last updated
Sep 8, 2026
Weakness Type
- CWE-476 NULL Pointer Dereference
References
- advisoryhttp://httpd.apache.org/security/vulnerabilities_24.html
- advisoryRHSA-2021:4257
- advisoryRHSA-2021:4613
- advisoryRHSA-2021:4614
- advisoryhttps://bugzilla.suse.com/1145740
FAQ
Common Questions.
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
Affected: HTTP Server (Apache) versions >= 2.4.46; Enterprise Manager Ops Center (Oracle) versions 12.4.0.0; Instantis Enterprisetrack (Oracle) versions 17.1, 17.2, 17.3, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including apache 2.4.47, apache 2.4.47-1, HTTP Server <=2.4.46.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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