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CVE record · CVE-2021-1647

Microsoft Defender Remote Code Execution Vulnerability

CVSS 7.8 HighCriticalIn CISA KEVEPSS 0.40 · 98th percentile

Critical, because:

  • In CISA’s KEV catalogue since 3 Nov 2021: it is known to be exploited.
  • CVSS score 7.8 (7.0 or more) and EPSS 0.40 (0.1 or more): a high score and a real chance of exploitation in the next 30 days.

How we decide what’s critical

Published by the CVE Program (CNA: microsoft) at 12 Jan 2021, 19:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
VendorProductVersions
Microsoft Microsoft System Center Endpoint Protection
  • affected N/A
Microsoft Microsoft System Center 2012 R2 Endpoint Protection
  • affected N/A
Microsoft Microsoft Security Essentials
  • affected N/A
Microsoft Microsoft System Center 2012 Endpoint Protection
  • affected N/A
Microsoft Windows Defender
  • affected N/A
Identifiers
CVE-2021-1647
CNA
microsoft
Tags
Published
12 Jan 2021
Updated
21 Oct 2025

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.8 High 3.1 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 CNA (microsoft)
  • CISA KEV Listed since 3 Nov 2021: known to be exploited.
  • EPSS 0.40, the 98th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 12 Jan 2021. New records show when each source confirmed them.

Sources

References from the CNA

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.