CVE-2020-9866: Apple Mac OS X

Critical severity, CVSS 9.8. EPSS: 1.9% chance of exploitation in the next 30 days.

A buffer overflow was addressed with improved bounds checking. This issue is fixed in macOS Catalina 10.15.6, Security Update 2020-004 Mojave, Security Update 2020-004 High Sierra. A buffer overflow may result in arbitrary code execution.

Affected products

• Apple Mac OS X: before 10.15.6 (fixed in 10.15.6)

Published 2020-10-27. Last modified 2026-06-17.