High 7.8Known exploited (CISA KEV)Published Jan 12, 2021

CVE-2021-1647Microsoft Defender Remote Code Execution Vulnerability

Updated under an hour ago (Oct 26, 2026, 6:23 PM ET)

Does this affect you?

It affects Microsoft System Center Endpoint Protection and 2 other products. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Nov 3, 2021; federal agencies had to remediate by Nov 17, 2021. Treat that date as your deadline.

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Exploited in the last 30 days

Microsoft Defender Remote Code Execution Vulnerability

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
Weakness (CWE): Not given
Known exploited: Added to CISA KEV Nov 3, 2021; federal remediation due Nov 17, 2021Apply updates per vendor instructions.
EPSS (exploitation in the next 30 days): 39.65% (percentile 99)
Assigned by: microsoft
NVD analysis: Analyzed
Record last updated: Oct 21, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Microsoft Microsoft System Center Endpoint Protection microsoft:system_center_endpoint_protection	all versions	CNA record
Microsoft Microsoft Security Essentials microsoft:security_essentials	all versions	CNA record
Microsoft Windows Defender microsoft:windows_defender	all versions	CNA record
microsoft windows_defender microsoft:windows_defender	all versions	NVD
microsoft security_essentials microsoft:security_essentials	all versions	NVD
microsoft system_center_endpoint_protection microsoft:system_center_endpoint_protection	all versions; 2012; 2012	NVD

References

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1647	vendor-advisory, patch
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1647	patch, vendor-advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1647	us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.