CVE-2021-4202 Use after free in kernel

What is CVE-2021-4202?

CVE-2021-4202 is a high-severity use after free vulnerability in Linux kernel, published on 25 Mar 2022. 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 nci_request in net/nfc/nci/core.c in NFC Controller Interface (NCI) in the Linux kernel. This flaw could allow a local attacker with user privileges to cause a data race problem while the device is getting removed, leading to a privilege escalation problem.

Weakness: CWE-416, CWE-362

Which versions are affected by CVE-2021-4202?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-4202?

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-2021-4202 being exploited?

There is no known exploitation of CVE-2021-4202 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 AZL-9237, DEBIAN-CVE-2021-4202, GHSA-gqgp-hh7h-fh5j, UBUNTU-CVE-2021-4202.