CVE-2021-30766: 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 was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.5, Security Update 2021-004 Catalina, Security Update 2021-005 Mojave. An application may be able to execute arbitrary code with kernel privileges.

Affected products

• Apple Mac OS X: from 10.14, 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, before 11.5 (fixed in 11.5)

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