CVE-2021-33574: debian debian_linux Use After Free

Vulnerability summary

CVE-2021-33574 is a critical (CVSS 9.8) Use After Free vulnerability in debian debian_linux. EPSS estimates a 3.52% chance of exploitation in the next 30 days, higher than 89.2% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 25-05-2021
   PublishedVulnerability first disclosed.
2. 14-10-2026
   Last modifiedVulnerability information updated.

Description

The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33 has a use-after-free. It may use the notification thread attributes object (passed through its struct sigevent parameter) after it has been freed by the caller, leading to a denial of service (application crash) or possibly unspecified other impact.

• 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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.