Security Update for Windows Defender (August 2021)

high Nessus Plugin ID 152427
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.


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


The Malware Protection Engine version of Microsoft Windows Defender installed on the remote Windows host is equal or prior to 1.1.18400.4. It is, therefore, affected by a unspecified privilege escalation vulnerability. An authenticated, local attacker can exploit this to gain administrator access to the system.


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

Plugin Details

Severity: High

ID: 152427

File Name: smb_nt_ms21_aug_win_defender.nasl

Version: 1.8

Type: local

Agent: windows

Family: Windows

Published: 8/10/2021

Updated: 8/25/2021

Dependencies: microsoft_windows_defender_win_installed.nbin

Risk Information

CVSS Score Source: CVE-2021-34471


Risk Factor: Medium

Score: 6.7


Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

Vector: AV:L/AC:L/Au:N/C:P/I:P/A:P

Temporal Vector: E:U/RL:OF/RC:C


Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

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

Required KB Items: installed_sw/Windows Defender

Exploit Ease: No known exploits are available

Patch Publication Date: 8/10/2021

Vulnerability Publication Date: 8/10/2021

Reference Information

CVE: CVE-2021-34471

IAVA: 2021-A-0372