CVE-2025-43400 is an out-of-bounds write vulnerability in Apple operating systems that was addressed by improved bounds checking. The flaw could be triggered by processing a maliciously crafted font, potentially causing unexpected application termination or memory corruption. This issue is fixed in multiple Apple OS versions including macOS Sonoma 14.8.1, macOS Tahoe 26.0.1, macOS Sequoia 15.7.1, visionOS 26.0.1, iOS 26.0.1, iPadOS 26.0.1, iOS 18.7.1, and iPadOS 18.7.1.