CVE-2024-40816 is a vulnerability identified in Apple macOS operating systems, specifically addressed in versions Monterey 12.7.6, Sonoma 14.6, and Ventura 13.6.8. The root cause is an out-of-bounds read error, a type of memory safety issue categorized under CWE-125, which occurs due to inadequate input validation. This flaw allows a local attacker with limited privileges (PR:L) to trigger an unexpected system shutdown, impacting system availability. The vulnerability does not require user interaction (UI:N) and does not affect confidentiality or integrity, but it can cause denial-of-service conditions by forcing the system to shut down unexpectedly. The CVSS v3.1 base score is 5.5, reflecting a medium severity level, with attack vector local (AV:L), low attack complexity (AC:L), and unchanged scope (S:U). Apple has fixed this issue by improving input validation to prevent the out-of-bounds read. There are no known exploits in the wild, but the vulnerability poses a risk to environments where local access is possible, such as shared workstations or multi-user systems. The lack of requirement for user interaction simplifies exploitation once local access is obtained. The vulnerability highlights the importance of robust input validation in preventing memory safety issues that can lead to system instability or denial of service.

The primary impact of CVE-2024-40816 is on system availability, as it allows a local attacker to cause unexpected shutdowns of affected macOS systems. This can disrupt business operations, especially in environments relying on continuous uptime such as servers, workstations in critical infrastructure, or enterprise environments. Although confidentiality and integrity are not compromised, the denial-of-service effect can lead to productivity loss, potential data loss if unsaved work is interrupted, and increased operational costs due to system downtime and recovery efforts. Organizations with multi-user macOS environments or those that allow local access to untrusted users are particularly vulnerable. The medium severity rating reflects the balance between the limited attack vector (local access required) and the impactful outcome (system shutdown). The absence of known exploits reduces immediate risk but does not eliminate the potential for future exploitation. Overall, the threat is significant for organizations that depend heavily on macOS systems for critical tasks and cannot tolerate unexpected outages.

To mitigate CVE-2024-40816, organizations should promptly apply the security updates released by Apple for macOS Monterey 12.7.6, Sonoma 14.6, and Ventura 13.6.8 or later versions that include the fix. Beyond patching, organizations should enforce strict local access controls to limit the number of users with local login privileges, reducing the attack surface. Implementing endpoint security solutions that monitor for unusual system behavior or unauthorized local access can help detect exploitation attempts. Regularly auditing user accounts and removing unnecessary local accounts can further reduce risk. Additionally, educating users about the risks of local access and maintaining strong physical security controls to prevent unauthorized device access are critical. For environments where uptime is critical, consider implementing system monitoring and automated recovery mechanisms to quickly respond to unexpected shutdowns. Finally, maintain up-to-date backups to mitigate potential data loss from abrupt system interruptions.