CVE-2021-26690: mod_session NULL pointer dereference

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 65.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-10 · updated 2026-06-17
Weakness: CWE-476

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

Apache HTTP Server: from 2.4.0 through 2.4.46
Debian Linux: 9.0, 10.0
Fedoraproject Fedora: 34, 35
Oracle Corporation Enterprise Manager Ops Center: 12.4.0.0
Oracle Instantis Enterprisetrack: 17.1, 17.2, 17.3
Oracle Corporation Oracle ZFS Storage Appliance Kit: 8.8

References

http://httpd.apache.org/security/vulnerabilities_24.html
http://www.openwall.com/lists/oss-security/2021/06/10/6
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%3E
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.html
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/202107-38
https://security.netapp.com/advisory/ntap-20210702-0001/
https://www.debian.org/security/2021/dsa-4937
https://www.oracle.com/security-alerts/cpuoct2021.html

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