CVE-2021-30728: Apple Mac OS X

High severity, CVSS 7.8. EPSS: 1.3% chance of exploitation in the next 30 days.

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.4, Security Update 2021-003 Catalina, Security Update 2021-004 Mojave. A malicious application may be able to execute arbitrary code with kernel privileges.

Affected products

• Apple Mac OS X: from 10.14.0, up to and including 10.14.5; from 10.15, up to and including 10.15.6; version 10.14.6 only; version 10.15.7 only
• Apple macOS: from 11.0.1, before 11.4 (fixed in 11.4)

Published 2021-09-08. Last modified 2026-06-17.