CVE-2021-4083 Use after free in kernel

What is CVE-2021-4083?

CVE-2021-4083 is a high-severity use after free vulnerability in Debian Debian Linux, published on 18 Jan 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A read-after-free memory flaw was found in the Linux kernel's garbage collection for Unix domain socket file handlers in the way users call close() and fget() simultaneously and can potentially trigger a race condition. This flaw allows a local user to crash the system or escalate their privileges on the system. This flaw affects Linux kernel versions prior to 5.16-rc4.

Weakness: CWE-362, CWE-416

Which versions are affected by CVE-2021-4083?

It affects 15 products.

Products include Debian Debian Linux, Linux kernel, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware and 9 more.

How do I fix CVE-2021-4083?

Upgrade to a fixed version.

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-2021-4083 being exploited?

There is no known exploitation of CVE-2021-4083 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

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

Also known as A-216408350, ASB-A-216408350, DEBIAN-CVE-2021-4083, GHSA-rcrv-64p3-px35, OESA-2021-1469, PUB-A-216408350 and 1 more.