CVE-2025-21360 is a high-severity elevation of privilege vulnerability affecting Microsoft AutoUpdate (MAU) for Mac. The vulnerability is classified under CWE-269, which pertains to improper privilege management. Specifically, this flaw allows an attacker with limited privileges on a Mac system to escalate their privileges to a higher level, potentially gaining administrative or system-level access. The CVSS 3.1 base score of 7.8 reflects a high impact, with the vector indicating that the attack requires local access (AV:L), low attack complexity (AC:L), and low privileges (PR:L) but no user interaction (UI:N). The vulnerability impacts confidentiality, integrity, and availability (all rated high), meaning an attacker could fully compromise the system, access sensitive data, modify or delete files, and disrupt system operations. The scope remains unchanged (S:U), so the impact is confined to the vulnerable component or system. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may rely on vendor updates or workarounds once available. Microsoft AutoUpdate is a component used to keep Microsoft software on Mac devices up to date, so this vulnerability could be leveraged by attackers who have gained limited access to escalate privileges and take full control of the affected Mac systems.

For European organizations, this vulnerability poses a significant risk, especially for those with Mac environments running Microsoft software such as Office 365, Teams, or other Microsoft applications that rely on Microsoft AutoUpdate. An attacker exploiting this flaw could gain elevated privileges on Mac endpoints, leading to potential data breaches, unauthorized access to corporate resources, and disruption of business operations. This is particularly concerning for sectors with stringent data protection requirements like finance, healthcare, and government agencies within Europe. The ability to escalate privileges without user interaction increases the risk of automated or stealthy attacks. Additionally, organizations with hybrid environments that include Mac devices may find their overall security posture weakened. The absence of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score underscores the urgency of addressing this vulnerability to prevent future exploitation.

European organizations should prioritize the following mitigation steps: 1) Monitor official Microsoft channels closely for patches or updates addressing CVE-2025-21360 and apply them promptly once released. 2) Until a patch is available, restrict local access to Mac systems running Microsoft AutoUpdate to trusted users only, minimizing the risk of an attacker gaining initial foothold. 3) Employ endpoint detection and response (EDR) solutions capable of monitoring for suspicious privilege escalation activities on Mac devices. 4) Implement strict access controls and least privilege principles to limit the impact of any compromised accounts. 5) Conduct regular audits of installed software versions and update management tools to ensure compliance with security policies. 6) Educate Mac users within the organization about the risks of local privilege escalation and encourage reporting of unusual system behavior. 7) Consider network segmentation to isolate Mac devices that handle sensitive data or critical functions, reducing lateral movement opportunities for attackers.