CVE-2026-55011 Microsoft Defender Remote Code Execution Vulnerability
An integer underflow in Microsoft Defender allows an unauthorized attacker to execute code locally on the affected system.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-55011?
CVE-2026-55011 is a high-severity vulnerability in Microsoft Malware Protection Engine, published on 14 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Integer underflow (wrap or wraparound) in Microsoft Defender allows an unauthorized attacker to execute code locally.
Weakness: CWE-191
Which versions are affected by CVE-2026-55011?
It affects 1 product.
Products include Microsoft Malware Protection Engine.
How do I fix CVE-2026-55011?
No fix has been published for CVE-2026-55011 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-55011 being exploited?
There is no known exploitation of CVE-2026-55011 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Malware Protection Engine
Sources
Also known as GHSA-9gvv-f74q-gxrr.