Defender for Endpoint and Antivirus
CVE-2026-55011: Microsoft Defender Remote Code Execution Vulnerability
Integer underflow (wrap or wraparound) in Microsoft Defender allows an unauthorized attacker to execute code locally.
Published
ExploitedNot in CISA KEV
Ransomware useNot reportedPer CISA
SeverityHIGHCVSS 3.1 7.8
EPSS0.47%Chance of exploitation in 30 days
Public exploitNot tracked
FixAvailable
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Microsoft Malware Protection Engine 1.1 | 1.1.26060.3008 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
Integer underflow (wrap or wraparound) in Microsoft Defender allows an unauthorized attacker to execute code locally.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 11 Oct 2026.