CVE-2025-43366 is a medium-severity vulnerability affecting Apple macOS, specifically related to an out-of-bounds read condition in the handling of coprocessor memory. The vulnerability arises due to 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). Exploiting this vulnerability could enable a malicious app to disclose sensitive data residing in the coprocessor memory, potentially leaking confidential information. The vulnerability requires local access (Attack Vector: Local) and user interaction (UI:R), but does not require privileges (PR:N). The scope is unchanged (S:U), meaning the impact is confined to the vulnerable component without affecting other system components. The CVSS v3.1 base score is 5.5, reflecting a medium severity level, with a high impact on confidentiality (C:H), but no impact on integrity (I:N) or availability (A:N). The issue has been addressed in macOS Tahoe 26 with improved bounds checking, though affected versions prior to this update are unspecified. No known exploits are currently reported in the wild. This vulnerability could be leveraged by attackers to extract sensitive coprocessor data, which might include cryptographic keys or other protected information, thereby undermining system security and user privacy.

For European organizations, this vulnerability poses a risk primarily to those using Apple macOS devices, especially in environments where sensitive data protection is critical, such as financial institutions, government agencies, and enterprises handling personal data under GDPR. Disclosure of coprocessor memory could lead to leakage of cryptographic keys or other sensitive information, potentially enabling further attacks such as data decryption or unauthorized access. Although exploitation requires local access and user interaction, the risk remains significant in scenarios involving insider threats or social engineering attacks that trick users into running malicious applications. The confidentiality breach could result in regulatory penalties, reputational damage, and operational disruption. However, the lack of impact on integrity and availability limits the threat to data exposure rather than system compromise or denial of service.

European organizations should prioritize updating all macOS devices to macOS Tahoe 26 or later, where the vulnerability is fixed with improved bounds checking. Implement strict application control policies to prevent installation or execution of untrusted or unsigned applications, reducing the risk of malicious apps exploiting this vulnerability. Employ endpoint detection and response (EDR) solutions capable of monitoring anomalous memory access patterns and application behaviors indicative of exploitation attempts. Conduct user awareness training to mitigate risks associated with social engineering and inadvertent execution of malicious software. Additionally, enforce least privilege principles to limit user permissions, minimizing the potential impact of local exploits. Regularly audit and inventory macOS devices to ensure timely patch deployment and compliance with security policies.