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TI-2021-18731 Aliases CVE-2021-42298GHSA-hrr5-6mf9-3wxh

Microsoft Defender Remote Code Execution Vulnerability

Priority MEDIUM 43CWE-94Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from Microsoft.

Summary

Microsoft Defender Remote Code Execution Vulnerability

Why it matters now

EPSS 0.05848 93rd percentileScored 2026-11-07
Fix Fixed Microsoft Malware Protection Engine (Microsoft): 1.1.18700.3

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftMicrosoft Malware Protection Engine1.1.0.0 to before 1.1.18700.31.1.18700.3Patch availableCNA
  • Microsoft Malware Protection Engine VendorMicrosoft Affected 1.1.0.0 to before 1.1.18700.3 Fixed in 1.1.18700.3 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:microsoft:malware_protection_engine:*:*:*:*:*:*:*:*before 1.1.18700.3VulnerableMicrosoft
  • cpe:2.3:a:microsoft:malware_protection_engine:*:*:*:*:*:*:*:* Versions before 1.1.18700.3 Vulnerable ·Microsoft

Remediation

  • Fix · CNA Microsoft Malware Protection Engine (Microsoft) Fixed in 1.1.18700.3

Vendor assessments

Microsoft

Microsoft's page for this CVE →

Impact
Remote Code Execution
Exploited
No
Publicly disclosed
No
Exploitability
Exploitation More Likely
ProductStatusPlan or fix
Microsoft Malware Protection EngineFixed 1.1.18700.3 · Security Update

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-42298
  2. 2026-10-03 Alias added: GHSA-hrr5-6mf9-3wxh

References

Patch 2

  • TI-2026-29727 Microsoft Defender Elevation of Privilege Vulnerability KEVCVSS 3.1HIGH 7.8
  • TI-2017-06074 Out-of-bounds write in Microsoft Malware Protection Engine KEVCVSS 3.1HIGH 7.8
  • TI-2017-00265 Memory corruption in Microsoft Malware Protection Engine CVSS 3.0HIGH 7.8
  • TI-2026-48742 Microsoft Defender Elevation of Privilege Vulnerability CVSS 3.1HIGH 7.8
  • TI-2026-37344 Microsoft Defender Elevation of Privilege Vulnerability CVSS 3.1HIGH 7.8
  • TI-2017-06072 Memory corruption in Microsoft Malware Protection Engine CVSS 3.0HIGH 7.8
See all 30 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences