CVE-2025-43366 is a vulnerability identified in Apple macOS, specifically related to an out-of-bounds read condition in the handling of coprocessor memory. The root cause is insufficient bounds checking, which allows an application to read memory outside the intended buffer boundaries. This flaw is categorized under CWE-125 (Out-of-bounds Read). The vulnerability was addressed by Apple in the macOS Tahoe 26 update, which implemented improved bounds checking to prevent unauthorized memory disclosure. The CVSS v3.1 base score is 5.5 (medium), with an attack vector of local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), high confidentiality impact (C:H), and no impact on integrity or availability (I:N/A:N). This means an attacker must have local access to the system and trick a user into running a malicious app to exploit the flaw. Successful exploitation could lead to disclosure of sensitive coprocessor memory contents, potentially exposing cryptographic keys or other protected information processed by the coprocessor. No known exploits have been reported in the wild as of the publication date. The vulnerability affects unspecified macOS versions prior to the patch release, so organizations should assume all current versions before Tahoe 26 are vulnerable. This vulnerability is significant because coprocessors often handle sensitive operations such as encryption, secure boot, or biometric data processing, and memory disclosure could undermine system security assurances.

For European organizations, the primary impact of CVE-2025-43366 is the potential unauthorized disclosure of sensitive information stored or processed by the macOS coprocessor. This could include cryptographic keys, biometric data, or other confidential information that, if leaked, might facilitate further attacks such as credential theft or data exfiltration. Although exploitation requires local access and user interaction, the risk is elevated in environments where macOS devices are used for sensitive operations or where attackers may gain physical or remote access to user machines. Sectors such as finance, government, healthcare, and critical infrastructure could be particularly affected due to the sensitivity of the data involved. The vulnerability does not affect system integrity or availability, so it is less likely to cause direct service disruption but could lead to significant confidentiality breaches. Given the widespread use of Apple devices in European enterprises and public sector organizations, failure to patch could expose them to targeted attacks or insider threats leveraging this vulnerability.

To mitigate CVE-2025-43366, European organizations should prioritize updating all macOS devices to macOS Tahoe 26 or later, where the vulnerability is fixed with improved bounds checking. Until updates are applied, organizations should enforce strict application control policies to prevent installation or execution of untrusted or unsigned applications that could exploit this vulnerability. Employ endpoint protection solutions capable of detecting anomalous local app behavior and monitor for suspicious user activity that might indicate exploitation attempts. Limit local user privileges and restrict physical and remote access to macOS devices to reduce the risk of local exploitation. Additionally, educate users about the risk of running untrusted applications and the importance of user interaction in the attack chain. For environments with coprocessor-dependent security features, consider additional monitoring of cryptographic operations and audit logs for signs of compromise. Regularly review and update security policies to incorporate this vulnerability and ensure timely patch management.