CVE-2025-43331 is a vulnerability identified in Apple macOS, specifically addressed in the macOS Tahoe 26 release. The flaw stems from a downgrade issue related to code-signing restrictions, which are critical mechanisms macOS uses to verify the integrity and authenticity of applications. Due to this downgrade issue, a malicious or compromised application may bypass these enhanced code-signing checks and gain unauthorized access to protected user data. The vulnerability is categorized under CWE-862, which refers to improper authorization, indicating that the system fails to correctly enforce access controls. The CVSS v3.1 base score is 4.0 (medium severity), with the vector indicating local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and confidentiality impact limited to partial information disclosure (C:L) without affecting integrity or availability. No known exploits have been reported in the wild at this time, and affected versions are unspecified, though the fix is implemented in macOS Tahoe 26. This vulnerability could allow an attacker with local access to the system to read sensitive user data that should otherwise be protected by macOS security mechanisms, potentially leading to privacy violations or further targeted attacks.

For European organizations, this vulnerability poses a risk primarily in environments where macOS devices are used, such as in creative industries, software development, and executive workstations. Unauthorized access to protected user data could lead to leakage of sensitive corporate information, personal data of employees or customers, and intellectual property. Given the medium severity and local attack vector, the threat is more significant in scenarios where attackers have physical or local network access to macOS systems, such as in shared workspaces or through compromised insider devices. The confidentiality breach could undermine compliance with GDPR and other data protection regulations in Europe, potentially resulting in legal and financial repercussions. While the vulnerability does not affect system integrity or availability, the exposure of protected data could facilitate social engineering, identity theft, or lateral movement within networks.

European organizations should prioritize updating all macOS devices to macOS Tahoe 26 or later, where the vulnerability is fixed. Since the attack requires local access, enforcing strict physical security controls and endpoint protection policies is essential. Implementing device encryption and strong user authentication can reduce the risk of unauthorized local access. Organizations should also audit installed applications and restrict the installation of untrusted or unsigned software to minimize the risk of malicious apps exploiting this flaw. Employing endpoint detection and response (EDR) solutions capable of monitoring unusual file access patterns or code-signing anomalies can help detect exploitation attempts. Regular security awareness training should emphasize the risks of local attacks and the importance of safeguarding devices. Finally, organizations should maintain up-to-date asset inventories to quickly identify and remediate vulnerable macOS systems.