CVE-2026-41091: Microsoft Defender Elevation of Privilege Vulnerability

Overview

Severity
High (CVSS 7.8)
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Elevation of Privilege
Exploit Status
Actively Exploited
Exploitation Likelihood
Detected
Publicly Disclosed
Yes
Patch Tuesday
2026-May
Released
2026-05-19

Description

Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.

FAQ

What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges. References Identification Last version of the Microsoft Malware Protection Engine affected by this vulnerability 1.1.26030.3008 First version of the Microsoft Malware Protection Engine with this vulnerability addressed Version 1.1.26040.8 See Manage Updates Baselines Microsoft Defender Antivirus for more information. Microsoft Defender is disabled in my environment, why are vulnerability scanners showing that I am vulnerable to this issue? Vulnerability scanners are looking for specific binaries and version numbers on devices. Microsoft Defender files are still on disk even when disabled. Systems that have disabled Microsoft Defender are not in an exploitable state. Why is no action required to install this update? In response to a constantly changing threat landscape, Microsoft frequently updates malware definitions and the Microsoft Malware Protection Engine. In order to be effective in helping protect against new and prevalent threats, antimalware software must be kept up to date with these updates in a timely manner. For enterprise deployments as well as end users, the default configuration in Microsoft antimalware software helps ensure that malware definitions and the Microsoft Malware Protection Engine are kept up to date automatically. Product documentation also recommends that products are configured for automatic updating. Best practices recommend that customers regularly verify whether software distribution, such as the automatic deployment of Microsoft Malware Protection Engine updates and malware definitions, is working as expected in their environment. How often are the Microsoft Malware Protection Engine and malware definitions updated? Microsoft typically releases an update for the Microsoft Malware Protection Engine once a month or as needed to protect against

Affected Products (1)

System Center

  • Microsoft Malware Protection Engine

Acknowledgments

<a href="https://github.com/void2012 "> Damir Moldovanov </a>, <a href="https://www.linkedin.com/in/andrewcdorman">ACD421</a> with Hollow Point Labs, <a href="https://www.linkedin.com/in/andrewcdorman">ACD421</a> with Hollow Point Labs, Anonymous, Diffract, <a href="https://x.com/sibusisosishi">Sibusiso</a> with <a href="https://www.ironsky.co.za/">Ironsky</a>

Revision History

  • 2026-05-19: Information published.