Zero-day vulnerability in Windows Defender

Insufficient Granularity of Access Control
CVE-2026-33825

Vulnerability details

Advisory: SB20260415129 - Privilege escalation in Microsoft Defender

Vulnerable component: Windows Defender

CVE-ID: CVE-2026-33825

CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-1220 - Insufficient Granularity of Access Control

Description:

The vulnerability allows a local user to escalate privileges on the target system.

The vulnerability exists due to insufficient granularity of access control in Microsoft Defender. A local user can gain elevated privileges on the system.

External links:

https://www.huntress.com/blog/nightmare-eclipse-intrusion

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.