CVE-2025-43353 is a heap corruption vulnerability in Apple macOS resulting from improper bounds checking when processing certain maliciously crafted strings. This vulnerability is categorized under CWE-787 (Out-of-bounds Write), indicating that the software writes data outside the boundaries of allocated memory buffers. Such heap corruption can destabilize the affected application or the operating system, potentially causing crashes or denial of service conditions. The vulnerability requires local access (Attack Vector: Local) with no privileges required (Privileges Required: None) but does require user interaction to trigger the flaw, such as opening or processing a malicious string input. The CVSS v3.1 base score is 5.5 (medium severity), reflecting the limited scope of impact—no confidentiality or integrity loss is expected, only availability impact (denial of service). Apple has fixed this issue by implementing improved bounds checks in macOS Sonoma 14.8 and macOS Sequoia 15.7. No public exploits or active exploitation in the wild have been reported to date. The affected macOS versions are unspecified but presumably include versions prior to the patched releases. This vulnerability highlights the risks of memory safety issues in system components that handle user-supplied data, emphasizing the importance of robust input validation and bounds checking.

For European organizations, the primary impact of CVE-2025-43353 is potential denial of service due to heap corruption triggered by processing maliciously crafted strings. This could lead to application crashes or system instability on vulnerable macOS endpoints, affecting availability of critical services or user productivity. Since exploitation requires local access and user interaction, remote exploitation risk is low, but insider threats or compromised local accounts could leverage this vulnerability. The absence of confidentiality or integrity impact reduces the risk of data breaches or unauthorized data modification. However, organizations relying heavily on macOS systems, especially in sectors like finance, technology, and government, could experience operational disruptions if this vulnerability is exploited. The lack of known exploits in the wild currently limits immediate risk, but the medium severity rating warrants timely remediation to prevent future attacks. Additionally, availability impacts in critical infrastructure or business environments could have cascading effects on service delivery and compliance with European data protection and operational resilience regulations.

1. Apply patches promptly by upgrading to macOS Sonoma 14.8 or macOS Sequoia 15.7, which contain the fix with improved bounds checking. 2. Restrict local user permissions to the minimum necessary to reduce the risk of unprivileged users triggering the vulnerability. 3. Educate users to avoid opening or processing untrusted or suspicious strings or files that could exploit this flaw. 4. Implement endpoint protection solutions capable of detecting anomalous application crashes or heap corruption indicators. 5. Monitor system logs and crash reports for signs of exploitation attempts or unusual application behavior. 6. Employ application whitelisting and restrict execution of unauthorized software to limit attack vectors. 7. For organizations with macOS in critical roles, consider network segmentation to isolate vulnerable systems and reduce exposure. 8. Maintain an inventory of macOS devices and their versions to ensure all are updated and compliant. 9. Coordinate with Apple support and security advisories for any emerging exploit information or additional patches.