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Vulnerabilities

Vulnerability · CVE-2021-1647

Microsoft Defender Remote Code Execution Vulnerability

Published Jan 12, 2021 · catalog updated Jun 16, 2026 · Microsoft Defender

Patch now

CVE-2021-1647 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Microsoft Defender against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
High7.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
39.39%
Remediation
Remediation guidance
Affected products
cpe microsoft/security essentials · cpe microsoft/system center endpoint protection · cpe microsoft/windows defender · vendor Microsoft Defender

Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/security essentialsversion unspecified
  • cpe microsoft/system center endpoint protection2012
  • cpe microsoft/windows defenderversion unspecified
  • vendor Microsoft Defenderversion unspecified

How to fix CVE-2021-1647

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-1647 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Microsoft Defender against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with microsoft/system center endpoint protection 2012. Apply updates per vendor instructions.

What should an analyst verify?

CWE-122: Heap-based Buffer Overflow; CWE-1285. EPSS 39.39%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jan 12, 2021 · Catalog

    Detected

    Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.

Sources

  • CISA KEVConfirmed exploitationCVE-2021-1647

    Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2021-1647

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-1647

    30-day exploitation probability 39.4%

    first.org
  • NIST NVDVulnerability recordCVE-2021-1647

    Microsoft Defender Remote Code Execution Vulnerability

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2021-1647

    Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.