macOS EUVD-2026-15100

Without a published CVSS score or EPSS probability data, the real-world risk must be assessed through available signals. The vulnerability requires local execution (an app must run on the target system), which constrains the attack surface compared to remote exploits. However, the technical impact is severe—file system modification can lead to complete system compromise, privilege escalation, and persistent backdoors. Apple's decision to patch this across three major OS versions simultaneously (Sequoia, Sonoma, and Tahoe) indicates they assessed this as a meaningful security issue warranting urgent remediation. The lack of public exploit code or KEV designation suggests this was not actively exploited in the wild at time of disclosure, though the nature of the vulnerability (local privilege boundary bypass) makes it attractive for sophisticated threats. Organizations should treat this as a high-priority patch based on Apple's release cadence and the severity of the potential impact, even absent CVSS metrics.

A user downloads what appears to be a legitimate productivity application from an unofficial source or social engineering vector. The application, once launched, exploits this permissions vulnerability to modify protected system directories—such as writing malicious code into system frameworks or kernel extensions, modifying launchd plist files for persistence, or altering security policies. Because the vulnerability allows normal user-context applications to bypass file system protections, the attacker achieves system-level compromise without needing to first elevate privileges through a separate local privilege escalation exploit. The local execution requirement means the attack chain typically involves social engineering or supply chain compromise rather than a direct remote network attack.