CVE-2026-69544 Windows SMB Client Elevation of Privilege Vulnerability

High 7.8 Published 8 Sep 2026 Updated 14 Oct 2026

A heap-based buffer overflow in the Windows SMB Client allows an authorized local attacker to elevate privileges.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-69544?

CVE-2026-69544 is a high-severity memory corruption vulnerability in Microsoft Windows 11 26h1, published on 8 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Heap-based buffer overflow in Windows SMB Client allows an authorized attacker to elevate privileges locally.

Weakness: CWE-122

Which versions are affected by CVE-2026-69544?

It affects 1 product.

Products include Microsoft Windows 11 26h1.

How do I fix CVE-2026-69544?

No fix has been published for CVE-2026-69544 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-69544 being exploited?

There is no known exploitation of CVE-2026-69544 in the wild and no public exploit code.

All Microsoft Windows 11 26h1 vulnerabilities

Sources

Also known as GHSA-4qx9-g9wc-38c2.