---
id: CVE-2021-34522
title: Microsoft Defender Remote Code Execution Vulnerability
summary: Microsoft Defender Remote Code Execution Vulnerability
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
vendor: microsoft
product: malware_protection_engine
affected:
  - malware_protection_engine < 1.1.18242.0
patched:
  - malware_protection_engine 1.1.18242.0
published: '2021-07-14'
updated: '2026-08-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-34522'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34522'
    label: secure@microsoft.com
  - url: >-
      https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34522
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.02699
epssPercentile: 0.85295
ingestedAt: '2026-08-10T16:41:17.479Z'
---

## Overview

Microsoft Defender Remote Code Execution Vulnerability

## Affected

- `malware_protection_engine < 1.1.18242.0`

## Remediation

Upgrade past the affected range:

- `malware_protection_engine 1.1.18242.0`