CVE-2021-26691

Apache HTTP Server mod_session response handling heap overflow

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

Categories

9.8
CVSS
Severity: Critical
CVSS 3.1 •
CVSS 2.0 •
EPSS 47.49% Top 5%
Vendor Advisory debian.org Vendor Advisory gentoo.org Vendor Advisory fedoraproject.org Vendor Advisory fedoraproject.org Vendor Advisory apache.org Vendor Advisory apache.org
Affected: Apache Software Foundation Apache HTTP Server
Published at:
Updated at:

References

Link Tags
http://httpd.apache.org/security/vulnerabilities_24.html vendor advisory
https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E vendor advisory mailing list release notes
https://lists.apache.org/thread.html/r50cae1b71f1e7421069036b213c26da7d8f47dd59874e3bd956959fe%40%3Cannounce.httpd.apache.org%3E mailing list
https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E mailing list
http://www.openwall.com/lists/oss-security/2021/06/10/7 third party advisory mailing list
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.html third party advisory mailing list
https://www.debian.org/security/2021/dsa-4937 vendor advisory mailing list third party advisory
https://security.gentoo.org/glsa/202107-38 third party advisory vendor advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/ vendor advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/ vendor advisory
https://www.oracle.com/security-alerts/cpuoct2021.html third party advisory patch
https://security.netapp.com/advisory/ntap-20210702-0001/ third party advisory
https://www.oracle.com/security-alerts/cpujan2022.html third party advisory patch

Frequently Asked Questions

What is the severity of CVE-2021-26691?
CVE-2021-26691 has been scored as a critical severity vulnerability.
How to fix CVE-2021-26691?
To fix CVE-2021-26691, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-26691 being actively exploited in the wild?
It is possible that CVE-2021-26691 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~47% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-26691?
CVE-2021-26691 affects Apache Software Foundation Apache HTTP Server.
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