CVE-2021-4095

Name: CVE-2021-4095
Creator: NVD / NIST
Published: 2022-03-10T17:44:53.563+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.39%

Last modified Jun 17, 2026

CVE-2021-4095 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. A NULL pointer dereference was found in the Linux kernel's KVM when dirty ring logging is enabled without an active vCPU context. An unprivileged local attacker on the host may use this flaw to cause a kernel oops condition and thus a denial of service by issuing a KVM_XEN_HVM_SET_ATTR ioctl. EPSS estimates a 0.39% chance of exploitation in the next 30 days.

Description

A NULL pointer dereference was found in the Linux kernel's KVM when dirty ring logging is enabled without an active vCPU context. An unprivileged local attacker on the host may use this flaw to cause a kernel oops condition and thus a denial of service by issuing a KVM_XEN_HVM_SET_ATTR ioctl. This flaw affects Linux kernel versions prior to 5.17-rc1.

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.39%

30.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	<= 5.16
Fedoraproject	Fedora	34
Fedoraproject	Fedora	35

References

http://www.openwall.com/lists/oss-security/2022/01/17/1Exploit, Mailing List, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2031194Exploit, Issue Tracking, Patch, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QIOQN7JJNN6ABIDGRSTVZA65MHRLMH2Q/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VT6573CGKVK3DU2632VVO5BVM4IU7SBV/
http://www.openwall.com/lists/oss-security/2022/01/17/1Exploit, Mailing List, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2031194Exploit, Issue Tracking, Patch, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QIOQN7JJNN6ABIDGRSTVZA65MHRLMH2Q/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VT6573CGKVK3DU2632VVO5BVM4IU7SBV/

Timeline

Published: Mar 10, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4095?

How severe is CVE-2021-4095?

CVE-2021-4095 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.39% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4095?

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-2021-4095?

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

Scan your code now

Source: NVD / NIST