The 'authorized attacker' label on CVE-2026-33825 is creating dangerous confusion. While CVSS 7.8 suggests a moderate technical severity, the operational reality is harsher: this vulnerability is functioning as post-exploitation tooling in active intrusions, and organizations should treat it as a KEV-level threat regardless of the score.
The attack works against systems where an attacker already has a foothold — achieved through phishing, credential theft, or supply chain compromise, which are routine in modern intrusions. This turns low-privileged access into SYSTEM-level control rapidly. If you're treating 'authorized' as a meaningful barrier, you're not seeing the actual threat landscape.
What makes this particularly dangerous is the detection asymmetry. Microsoft Defender's MpDefenderCore.exe generates continuous high-privilege operations across file system, registry, and process creation — legitimate activity that creates massive baseline noise. The product that should surface anomalies is the one being weaponized, and its own telemetry drowns out exploitation signals. If you're relying on Defender's logs to detect this, you're fighting blind. Kernel-mode ETW traces provide the visibility you need, but most organizations lack instrumentation for them.
There's a deeper architectural problem here. Defender accumulated privileged capabilities over years — filesystem hooks, registry monitoring, process injection for quarantine, kernel callbacks — added by different teams under shipping pressure. The authorization model never scaled to match the privilege level. This 'granularity of access control' failure isn't just a Defender problem; Microsoft's security stack shares code paths (WdBoot.sys, Windows Security Center), meaning exploitation here potentially provides pivot capability to tamper with other security components without triggering cross-integrity checks.
Your immediate actions: identify what percentage of your fleet is running unpatched Defender versions, then hunt for anomalous MpDefenderCore.exe behavior in the last 90 days using raw ETW traces — not Defender's own telemetry. If you lack that visibility, assume compromise and conduct retrospective hunting. The organizations most vulnerable to this are precisely those least equipped to detect it.