CVE-2026-33825

This vulnerability is a “permission check” problem in Microsoft Defender (the built-in security tool). If someone already has a certain level of access on a computer, the flaw may allow them to gain higher permissions and do more than they normally could. Think of it like a building where a person with a temporary badge can use a gap in the rules to get into restricted areas.

This matters to you if you use Microsoft Defender’s antimalware platform in Microsoft Windows environments, especially if your systems can be accessed by attackers who have already gotten some foothold. It affects Microsoft Corp Microsoft Defender Antimalware Platform, microsoft defender antimalware platform, and Microsoft Microsoft Defender Antimalware Platform. Because it is locally privilege-related, it most threatens organizations where machines are exposed to phishing, stolen credentials, remote access, or other ways attackers can gain initial access.

This is RED, meaning you should act quickly. It is already listed as actively exploited (“Known exploited in the wild” by CISA KEV) and the press indicates a public proof-of-concept exists, so attackers don’t need to guess for long. Prioritize patching and tightening access controls now rather than waiting for a routine update cycle.