CVE intelligence

CVE-2021-4083

Vulnerability intelligence

Published Jan 18, 2022Sources checked Oct 21, 2026

7.0HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2021-4083 and is rated High severity with a CVSS score of 7.0. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Ubuntu Security Notices guidance

Vendor revision: Oct 13, 2026

This update corrects flaws in the following subsystems: - IPv6 networking; - Netfilter; (CVE-2026-53131)

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2021-4083?

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.

Source: NVD