CVE-2026-45657 Windows Kernel Remote Code Execution Vulnerability

Critical 9.8 Published 9 Jun 2026 Updated 24 Sep 2026

An unauthorized attacker can execute code over a network due to a use-after-free vulnerability in the Windows Kernel.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-45657?

CVE-2026-45657 is a critical use after free vulnerability in Microsoft Windows 11 23h2, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Use after free in Windows Kernel allows an unauthorized attacker to execute code over a network.

Weakness: CWE-416, CWE-122

Which versions are affected by CVE-2026-45657?

It affects 6 products.

Products include Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows Server 2022, Microsoft Windows Server 2025.

How do I fix CVE-2026-45657?

No fix has been published for CVE-2026-45657 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2026-45657 being exploited?

There is no known exploitation of CVE-2026-45657 in the wild and no public exploit code.

All Microsoft Windows 11 23h2 vulnerabilities

Sources

Also known as GHSA-3r8r-9cjm-whj4.