CVE-2021-20317

Name: CVE-2021-20317
Creator: NVD / NIST
Published: 2021-09-27T11:15:07.357+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.4/10EPSS 0.37%

Last modified Jun 17, 2026

CVE-2021-20317 is a medium-severity vulnerability rated 4.4/10 on the CVSS scale. A flaw was found in the Linux kernel. A corrupted timer tree caused the task wakeup to be missing in the timerqueue_add function in lib/timerqueue.c. EPSS estimates a 0.37% chance of exploitation in the next 30 days.

Description

A flaw was found in the Linux kernel. A corrupted timer tree caused the task wakeup to be missing in the timerqueue_add function in lib/timerqueue.c. This flaw allows a local attacker with special user privileges to cause a denial of service, slowing and eventually stopping the system while running OSP.

Metrics

CVSS 3.1

4.4/10

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

EPSS Probability

0.37%

28.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	< 5.4
Linux	Linux Kernel	5.4
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=2005258Issue Tracking, Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=511885d7061eda3eb1faf3f57dcc936ff75863f1Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/12/msg00012.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.htmlMailing List, Third Party Advisory
https://www.debian.org/security/2022/dsa-5096Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2005258Issue Tracking, Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=511885d7061eda3eb1faf3f57dcc936ff75863f1Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/12/msg00012.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.htmlMailing List, Third Party Advisory
https://www.debian.org/security/2022/dsa-5096Third Party Advisory

Timeline

Published: Sep 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20317?

How severe is CVE-2021-20317?

CVE-2021-20317 has a CVSS score of 4.4/10 (MEDIUM severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20317?

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-2021-20317?

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

Scan your code now

Source: NVD / NIST