CVE-2025-43209: 
macOS vulnerability analysis and mitigation

CVE-2025-43209 is an out-of-bounds access vulnerability discovered in Apple's ICU (International Components for Unicode) component that affects multiple Apple operating systems. The vulnerability was disclosed on July 29, 2025, and was identified by Gary Kwong working with Trend Micro Zero Day Initiative. The affected systems include macOS Sequoia 15.6, iPadOS 17.7.9, iOS 18.6 and iPadOS 18.6, tvOS 18.6, macOS Sonoma 14.7.7, watchOS 11.6, visionOS 2.6, and macOS Ventura 13.7.7 (Apple Support, NVD).

The vulnerability is classified as an out-of-bounds access issue in the ICU component that was addressed with improved bounds checking. According to the CVSS 3.1 scoring by CISA-ADP, the vulnerability has received a Critical severity rating with a base score of 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). The vulnerability is associated with CWE-787 (Out-of-bounds Write) (NVD).

When exploited, the vulnerability can lead to an unexpected Safari crash when processing maliciously crafted web content. Given the high CVSS score and the nature of the vulnerability, it could potentially lead to arbitrary code execution or system compromise (Apple Support).

Apple has addressed this vulnerability by implementing improved bounds checking in the affected systems. Security updates have been released for all affected operating systems: macOS Sequoia 15.6, iPadOS 17.7.9, iOS 18.6 and iPadOS 18.6, tvOS 18.6, macOS Sonoma 14.7.7, watchOS 11.6, visionOS 2.6, and macOS Ventura 13.7.7. Users are advised to update their devices to these latest versions to protect against this vulnerability (Apple Support).