CVE-2021-26690

Name: CVE-2021-26690
Creator: NVD / NIST
Published: 2021-06-10T07:15:07.543+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 65.07%

Last modified Jun 17, 2026

CVE-2021-26690 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 65.07% chance of exploitation in the next 30 days.

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

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

65.07%

99.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Vendor	Product	Versions
Apache	Http Server	>= 2.4.0, <= 2.4.46
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Fedoraproject	Fedora	34
Fedoraproject	Fedora	35
Oracle	Enterprise Manager Ops Center	12.4.0.0
Oracle	Instantis Enterprisetrack	17.1
Oracle	Instantis Enterprisetrack	17.2
Oracle	Instantis Enterprisetrack	17.3
Oracle	Zfs Storage Appliance Kit	8.8

References

http://httpd.apache.org/security/vulnerabilities_24.htmlRelease Notes, Vendor Advisory
http://www.openwall.com/lists/oss-security/2021/06/10/6Mailing List, Third Party Advisory
https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E
https://lists.apache.org/thread.html/rae406c1d19c0dfd3103c96923dadac2af1cd0bad6905ab1ede153865%40%3Cannounce.httpd.apache.org%3E
https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3EMailing List, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/
https://security.gentoo.org/glsa/202107-38Third Party Advisory
https://security.netapp.com/advisory/ntap-20210702-0001/Third Party Advisory
https://www.debian.org/security/2021/dsa-4937Mailing List, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.htmlThird Party Advisory
http://httpd.apache.org/security/vulnerabilities_24.htmlRelease Notes, Vendor Advisory
http://www.openwall.com/lists/oss-security/2021/06/10/6Mailing List, Third Party Advisory
https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E
https://lists.apache.org/thread.html/rae406c1d19c0dfd3103c96923dadac2af1cd0bad6905ab1ede153865%40%3Cannounce.httpd.apache.org%3E
https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3EMailing List, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/
https://security.gentoo.org/glsa/202107-38Third Party Advisory
https://security.netapp.com/advisory/ntap-20210702-0001/Third Party Advisory
https://www.debian.org/security/2021/dsa-4937Mailing List, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.htmlThird Party Advisory

Timeline

Published: Jun 10, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26690?

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

How severe is CVE-2021-26690?

CVE-2021-26690 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 65.07% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26690?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26690?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST