CVE-2021-4083: debian debian_linux Use After Free

Vulnerability summary

CVE-2021-4083 is a high (CVSS 7.0) Use After Free vulnerability in debian debian_linux. EPSS estimates a 0.31% chance of exploitation in the next 30 days, higher than 23.9% of scored vulnerabilities.

Timeline

1. 18-01-2022
   PublishedVulnerability first disclosed.
2. 03-08-2024
   Last modifiedVulnerability information updated.

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.

• CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
• CWE-362Concurrent Execution using Shared Resource with Improper SynchronizationThe product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.