CVE-2022-42821 is a logic vulnerability in Apple macOS Gatekeeper, a security feature designed to prevent untrusted or malicious applications from running on macOS systems. Gatekeeper enforces code signing and verifies downloaded applications to ensure they come from identified developers and have not been tampered with. This vulnerability arises from a flaw in the logic of Gatekeeper's verification process, allowing a malicious app to bypass these security checks. Specifically, the issue is classified under CWE-693 (Protection Mechanism Failure), indicating that the intended security controls can be circumvented due to improper implementation. The flaw affects multiple macOS versions, including Monterey 12.6.2, Big Sur 11.7.2, and Ventura 13, with patches released in these versions to address the problem. The CVSS v3.1 base score is 5.5 (medium severity), with vector AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N, meaning the attack requires local access, low attack complexity, no privileges, user interaction, and impacts integrity but not confidentiality or availability. Exploitation involves tricking a user into running a malicious app that Gatekeeper would normally block, allowing the app to execute potentially harmful code without proper validation. No known exploits in the wild have been reported to date. This vulnerability undermines the trust model of macOS application security, potentially enabling attackers to deliver and execute malicious payloads more easily on vulnerable systems.

For European organizations, this vulnerability poses a risk primarily to the integrity of macOS systems. Since Gatekeeper is a core defense against unauthorized software execution, bypassing it can allow attackers to run malicious code that could lead to unauthorized modifications, persistence, or lateral movement within networks. Organizations relying on macOS endpoints—such as creative industries, software development firms, and enterprises with mixed OS environments—may face increased risk of targeted attacks or malware infections. Although the vulnerability does not directly impact confidentiality or availability, the integrity compromise can facilitate further exploitation, including data manipulation or deployment of additional malware. The requirement for local access and user interaction limits remote exploitation but does not eliminate risk, especially in environments where users may be socially engineered to run untrusted applications. Given the widespread use of macOS in certain European sectors and the strategic importance of protecting endpoint integrity, this vulnerability could be leveraged in targeted attacks against high-value organizations or individuals.

1. Immediate patching: Ensure all macOS systems are updated to versions Monterey 12.6.2, Big Sur 11.7.2, Ventura 13, or later where the vulnerability is fixed. 2. Application whitelisting: Implement strict application control policies using tools like Apple’s Endpoint Security framework or third-party solutions to restrict execution to trusted applications only. 3. User training: Educate users about the risks of running untrusted applications and the importance of Gatekeeper warnings to reduce successful social engineering attempts. 4. Monitoring and detection: Deploy endpoint detection and response (EDR) solutions capable of identifying suspicious application execution patterns that may indicate Gatekeeper bypass attempts. 5. Restrict local access: Limit physical and remote local access to macOS systems to trusted personnel only, reducing the attack surface for local exploitation. 6. Use of notarization: Enforce policies that only allow execution of notarized applications, adding an additional layer of verification beyond Gatekeeper. 7. Incident response readiness: Prepare for potential incidents by having procedures to quickly isolate and remediate compromised macOS endpoints.