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TI-2026-29727 Aliases CVE-2026-41091GHSA-h776-j9jw-992p

Microsoft Defender Elevation of Privilege Vulnerability

Priority CRITICAL 93Exploited in the wildCWE-59Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Privilege escalation
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

Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.

Why it matters now

Exploitation Active In CISA KEV since 2026-05-20CISA due date 2026-06-03
EPSS 0.08202 94th percentileScored 2026-11-07
Fix Fixed Microsoft Malware Protection Engine (Microsoft): 1.1.26040.8

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Active
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftMicrosoft Malware Protection Engine1.1.0.0 to before 1.1.26040.81.1.26040.8Patch availableCNA
  • Microsoft Malware Protection Engine VendorMicrosoft Affected 1.1.0.0 to before 1.1.26040.8 Fixed in 1.1.26040.8 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:microsoft:malware_protection_engine:*:*:*:*:*:*:*:*1.1.26030.3008 to before 1.1.26040.8VulnerableMicrosoft
  • cpe:2.3:a:microsoft:malware_protection_engine:*:*:*:*:*:*:*:* Versions 1.1.26030.3008 to before 1.1.26040.8 Vulnerable ·Microsoft

Remediation

  • Fix · CNA Microsoft Malware Protection Engine (Microsoft) Fixed in 1.1.26040.8

Vendor assessments

Microsoft

Microsoft's page for this CVE →

Impact
Elevation of Privilege
Exploited
Yes
Publicly disclosed
Yes
Exploitability
Exploitation Detected
ProductStatusPlan or fix
Microsoft Malware Protection EngineFixed 1.1.26040.8 · Security Update

Timeline

  1. 2026-05-20 Added to CISA KEV
  2. 2026-10-02 Threatist record created from CVE-2026-41091
  3. 2026-10-03 Alias added: GHSA-h776-j9jw-992p
  4. 2026-10-25 EPSS moved to the 90th–95th percentile

References

Patch 1

Advisory 1

  • 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
  • TI-2017-06075 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