Remote code execution in Microsoft Defender

Published: 2021-01-12
Risk Critical
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2021-1647
Exploitation vector Network
Public exploit This vulnerability is being exploited in the wild.
Vulnerable software
Microsoft Security Essentials
Client/Desktop applications / Antivirus software/Personal firewalls

Windows Defender
Client/Desktop applications / Antivirus software/Personal firewalls

Microsoft System Center Endpoint Protection
Server applications / DLP, anti-spam, sniffers

Vendor Microsoft

Security Advisory

This security advisory describes one critical risk vulnerability.

1) Input validation error

Risk: Critical

CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C] [PCI]

CVE-ID: CVE-2021-1647

CWE-ID: CWE-20 - Improper Input Validation

Exploit availability: No


The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can pass specially crafted input to the application and execute arbitrary code on the system.

Note, the vulnerability is being actively exploited in the wild.


Install updates from vendor's website.

Vulnerable software versions

Microsoft Security Essentials: All versions

Windows Defender: for Windows 8.1, for Windows 10, Windows 10 1511, Windows 10 1607, Windows Server 2016, Windows 10 1703, for Windows RT 8.1, for Windows Server 2019, on Windows 7 for 32-bit Systems Service Pack 1, on Windows Server 2008, on Windows Server 2012

Microsoft System Center Endpoint Protection: 2012, 2012 R2

CPE External links

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.