Integer underflow in Microsoft Malware Protection Engine - CVE-2026-55011
Published: July 17, 2026
Vulnerability identifier: #VU138297
CSH Severity: High
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-55011
CWE-ID: CWE-191
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to integer underflow in Microsoft Defender. A remote attacker can trick a victim to open a specially crafted file, trigger integer underflow and execute arbitrary code on the target system.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
Affected software
Microsoft Malware Protection Engine
How to mitigate CVE-2026-55011
Install updates from vendor's website.
Microsoft Malware Protection Engine - update to 1.1.26060.3008