CVE-2021-20226

Name: CVE-2021-20226
Creator: NVD / NIST
Published: 2021-02-23T17:15:13.66+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.44%

Last modified Jun 17, 2026

CVE-2021-20226 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. A use-after-free flaw was found in the io_uring in Linux kernel, where a local attacker with a user privilege could cause a denial of service problem on the system The issue results from the lack of validating the existence of an object prior to performing operations on the object by not incrementing the file reference counter while in use. The highest threat from this vulnerability is to data integrity, confidentiality and system availability.. EPSS estimates a 0.44% chance of exploitation in the next 30 days.

Description

A use-after-free flaw was found in the io_uring in Linux kernel, where a local attacker with a user privilege could cause a denial of service problem on the system The issue results from the lack of validating the existence of an object prior to performing operations on the object by not incrementing the file reference counter while in use. The highest threat from this vulnerability is to data integrity, confidentiality and system availability.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.44%

35.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	>= 5.5, < 5.8.18
Linux	Linux Kernel	>= 5.9.0, < 5.9.3
Netapp	Cloud Backup	All versions

References

https://bugzilla.redhat.com/show_bug.cgi?id=1873476Issue Tracking, Third Party Advisory
https://security.netapp.com/advisory/ntap-20210401-0001/Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1873476Issue Tracking, Third Party Advisory
https://security.netapp.com/advisory/ntap-20210401-0001/Third Party Advisory

Timeline

Published: Feb 23, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20226?

How severe is CVE-2021-20226?

CVE-2021-20226 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.44% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20226?

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-2021-20226?

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

Scan your code now

Source: NVD / NIST