macOS CVE-2026-20631

Authenticated user with low-privilege access to macOS Tahoe 26.3 or earlier. No user interaction required. Attacker can elevate privileges to gain high-impact code execution, data exfiltration, and system compromise.

While a precise CVSS score and vector are not provided, the privilege escalation nature of this vulnerability suggests moderate to high severity in real-world contexts. The attack vector is local-only (requiring prior system access), which reduces opportunistic exploitation risk compared to remote vulnerabilities. The absence of reported active exploitation, public proof-of-concept code, or KEV (Known Exploited Vulnerability) status indicates low immediate threat landscape activity. The logic-based nature of the flaw suggests it likely requires moderate attack complexity and specific conditions to trigger. Risk priority should be elevated for systems where local user compromise is credible (shared systems, development environments, or organizations with high insider threat concerns), but lower for air-gapped or tightly controlled endpoints. The availability of a patch (macOS Tahoe 26.4) significantly mitigates risk for organizations with rapid patching capabilities.

An attacker with a standard user account on an affected macOS Tahoe system exploits the insufficient privilege checks to escalate their access to administrator or root-level permissions. For example, the attacker could invoke a system utility or daemon that fails to properly validate their permissions, allowing them to execute privileged operations such as modifying system files, installing kernel extensions, or accessing sensitive data restricted to root. This scenario is particularly relevant in multi-user environments (shared development machines, lab systems) or following initial compromise via phishing, where the attacker gains standard user access and then leverages this logic flaw to gain full system control without requiring the user's administrative password.