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Security Update for Windows Defender (May 2026) (CVE-2026-41091)

high Nessus Plugin ID 316462

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Synopsis

An antimalware application installed on the remote host is affected by a privilege escalation vulnerability.

Description

The Malware Protection Engine version of Microsoft Windows Defender installed on the remote Windows host is prior to 1.1.26040.8. It is, therefore, affected by a privilege escalation vulnerability:

 - Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally. (CVE-2026-41091)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Enable automatic updates to update the malware engine for the relevant antimalware applications. Refer to Knowledge Base Article 2510781 for information on how to verify that MMPE has been updated.

See Also

http://www.nessus.org/u?b74f81ae

Plugin Details

Severity: High

ID: 316462

File Name: smb_nt_ms26_may_win_defender.nasl

Version: 1.3

Type: Local

Agent: windows

Published: 5/22/2026

Updated: 6/16/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Critical

Score: 9.0

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.9

Vector: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C

CVSS Score Source: CVE-2026-41091

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 7.5

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:H/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:microsoft:windows, cpe:/a:microsoft:windows_defender

Required KB Items: installed_sw/Windows Defender

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 5/19/2026

Vulnerability Publication Date: 5/19/2026

CISA Known Exploited Vulnerability Due Dates: 6/3/2026

Reference Information

CVE: CVE-2026-41091