CVE-2025-43331 is a vulnerability identified in Apple macOS related to a downgrade issue that compromises the enforcement of code-signing restrictions. Code-signing is a security mechanism that ensures only trusted and verified applications can execute sensitive operations or access protected resources. The vulnerability arises because an application can bypass or downgrade these code-signing checks, thereby gaining unauthorized access to protected user data. This flaw does not require any privileges or user interaction, but it does require local access to the system, meaning an attacker must already have some foothold on the device. Apple addressed this issue in macOS Tahoe 26 by implementing additional code-signing restrictions to prevent such downgrade attacks. The vulnerability is classified under CWE-862, which relates to improper authorization, indicating that the system fails to properly verify whether an app is authorized to access certain data. The CVSS v3.1 base score is 4.0 (medium severity), with attack vector local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and only confidentiality impact (C:L), with no impact on integrity or availability. There are no known exploits in the wild at this time, and no patch links were provided, but the fix is included in macOS Tahoe 26.

The primary impact of CVE-2025-43331 is unauthorized access to protected user data, which compromises user privacy and confidentiality. Although the vulnerability does not affect data integrity or system availability, the exposure of sensitive information can lead to further attacks such as identity theft, espionage, or targeted phishing campaigns. Since exploitation requires local access but no privileges or user interaction, attackers who have already gained limited access to a macOS device could escalate their capabilities by accessing protected data without authorization. This can be particularly damaging in environments where sensitive personal or corporate data is stored on macOS devices, such as in enterprises, government agencies, and research institutions. The medium severity rating reflects the limited scope of impact and the requirement for local access, but organizations should not underestimate the privacy risks. The absence of known exploits reduces immediate risk but does not eliminate the potential for future exploitation.

To mitigate CVE-2025-43331, organizations and users should upgrade all affected macOS systems to macOS Tahoe 26 or later, where the vulnerability is fixed with enhanced code-signing restrictions. Since the vulnerability requires local access, enforcing strict endpoint security controls such as strong authentication, device encryption, and endpoint detection and response (EDR) solutions can reduce the risk of initial compromise. Limiting user privileges and employing application whitelisting can also help prevent untrusted applications from running. Regularly auditing installed applications and monitoring for unusual access to protected data can provide early detection of exploitation attempts. Additionally, organizations should educate users about the risks of installing untrusted software and maintain up-to-date backups to mitigate potential data loss from related attacks. Finally, Apple should be monitored for any official patches or security advisories to ensure timely deployment.