CVE-2026-65774

CVE-2026-65774 is a heap-based buffer overflow in the Windows Installer engine that executes within the TrustedInstaller service context—meaning successful exploitation grants SYSTEM-level privileges. This is not a new vulnerability class; it's the latest expression of a recurrence pattern documented across multiple CVEs in the installer engine over the past decade. The critical insight is that the vulnerability's severity derives not from the heap overflow itself, but from the privilege topology in which it executes. A bounded-memcpy bug in an unprivileged service is a security concern; in TrustedInstaller it's a franchise. The TrustedInstaller model was designed for an era when installation was a discrete, administrator-controlled event. That threat model has silently rotted—automated updates, CI/CD pipelines publishing MSI artifacts, and browsers downloading installers from untrusted network contexts now feed untrusted input into a SYSTEM-privileged parsing engine by design. The recurrence is not accidental. The MSI engine contains

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