CVE-2021-30738: Apple Mac OS X

Medium severity, CVSS 5.5. EPSS: 0.3% chance of exploitation in the next 30 days.

A malicious application may be able to overwrite arbitrary files. This issue is fixed in macOS Big Sur 11.4, Security Update 2021-004 Mojave. An issue with path validation logic for hardlinks was addressed with improved path sanitization.

Affected products

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

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