CVE-2021-1834: Apple Mac OS X

Critical severity, CVSS 9.8. EPSS: 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 11.3, Security Update 2021-002 Catalina, Security Update 2021-003 Mojave. A malicious application may be able to execute arbitrary code with kernel privileges.

Affected products

• Apple Mac OS X: version 10.14 only; version 10.14.0 only; version 10.14.1 only; version 10.14.2 only; version 10.14.3 only; version 10.14.4 only; …
• Apple macOS: from 11.0, before 11.3 (fixed in 11.3)

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