CVE-2024-40821 is a vulnerability in Apple macOS that arises from an access control issue where third-party app extensions do not receive the correct sandbox restrictions. Sandboxing is a critical security mechanism designed to limit the capabilities of applications and extensions, preventing them from performing unauthorized actions or accessing sensitive system resources. In this case, the failure to apply proper sandbox restrictions means that malicious or compromised extensions could operate with elevated privileges or access beyond their intended scope. This can lead to severe consequences including unauthorized access to confidential data, modification or deletion of critical files, and disruption of system availability. The vulnerability affects multiple macOS versions prior to the patched releases: Sonoma 14.6, Monterey 12.7.6, and Ventura 13.6.8. The CVSS v3.1 score of 8.4 reflects a high severity, with an attack vector limited to local access (AV:L), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). This means an attacker with local access could exploit this flaw to fully compromise the system. The vulnerability is categorized under CWE-281 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating a failure in enforcing security boundaries. While no exploits are currently known in the wild, the vulnerability’s nature and severity make it a critical risk for environments where macOS is used, especially those running third-party extensions that may be untrusted or less vetted. The issue was addressed by Apple through additional sandbox restrictions in the specified patched macOS versions.

For European organizations, the impact of CVE-2024-40821 can be significant, particularly for those relying on macOS devices in their IT infrastructure. The vulnerability allows malicious third-party extensions to bypass sandbox restrictions, potentially leading to unauthorized data access, data corruption, or system disruption. This could result in data breaches involving sensitive personal data protected under GDPR, intellectual property theft, or operational downtime. Sectors such as finance, healthcare, government, and critical infrastructure are especially at risk due to the sensitivity of their data and the regulatory implications of breaches. The local attack vector means that attackers need some form of local access, which could be achieved through phishing, social engineering, or insider threats. Once exploited, the attacker could escalate privileges and move laterally within the network, increasing the scope of compromise. The lack of required user interaction lowers the barrier for exploitation, making automated or stealthy attacks feasible. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly once the vulnerability is public. Therefore, European organizations must prioritize patching and monitoring to mitigate potential impacts.

1. Apply the latest Apple security updates immediately: upgrade to macOS Sonoma 14.6, Monterey 12.7.6, Ventura 13.6.8, or later versions where the vulnerability is fixed. 2. Audit and restrict the installation of third-party app extensions, especially those from untrusted sources. Implement application whitelisting or endpoint protection solutions that can monitor extension behavior. 3. Employ strict device management policies using Mobile Device Management (MDM) solutions to control software installation and enforce security configurations. 4. Monitor system logs and endpoint telemetry for unusual activities indicative of sandbox escape attempts or privilege escalation. 5. Educate users about the risks of installing unverified extensions and enforce least privilege principles to limit local access opportunities for attackers. 6. Conduct regular vulnerability assessments and penetration testing focused on macOS environments to detect potential exploitation paths. 7. For critical systems, consider network segmentation to limit lateral movement if a device is compromised. 8. Maintain up-to-date backups and incident response plans to quickly recover from potential breaches.