CVE-2021-30977: Apple Mac OS X

High severity, CVSS 7.8. EPSS: 1.5% chance of exploitation in the next 30 days.

A buffer overflow was addressed with improved bounds checking. This issue is fixed in macOS Monterey 12.1, Security Update 2021-008 Catalina, macOS Big Sur 11.6.2. A malicious application may be able to execute arbitrary code with kernel privileges.

Affected products

• Apple Mac OS X: from 10.15, before 10.15.7 (fixed in 10.15.7); version 10.15.7 only
• Apple macOS: from 11.0, before 11.6.2 (fixed in 11.6.2); from 12.0, before 12.3 (fixed in 12.3)

Published 2021-08-24. Last modified 2026-06-17.