CVE-2021-20226 Use after free in kernel

What is CVE-2021-20226?

CVE-2021-20226 is a high-severity use after free vulnerability in Linux kernel, published on 23 Feb 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-416

Which versions are affected by CVE-2021-20226?

It affects 2 products.

Products include Linux kernel, Netapp Cloud Backup.

How do I fix CVE-2021-20226?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-20226 being exploited?

There is no known exploitation of CVE-2021-20226 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-20226, GHSA-vwgf-gfhw-h447, UBUNTU-CVE-2021-20226.