Is CVE-2026-45657 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-45657 being exploited in the wild.

How severe is CVE-2026-45657?

Critical severity, with a CVSS score of 9.8, published 9 June 2026.

Which products and versions are affected?

Microsoft Windows All supported versions.

Is there a fix for CVE-2026-45657?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-45657 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-45657?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-45657: Microsoft Windows Kernel use after free remote code execution

CVE-2026-45657 · Severity: critical · CVSS 9.8 · Published 2026-06-09

A critical vulnerability has been identified in the Windows operating system kernel, which manages the core operations of the computer. This flaw allows a remote attacker to gain full control over a system without needing any user interaction or login credentials. An exploit could lead to a total compromise of the affected server or workstation, resulting in data theft, service disruption, or the installation of malware.

Quick answers

Is CVE-2026-45657 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-45657 being exploited in the wild.
How severe is CVE-2026-45657?: Critical severity, with a CVSS score of 9.8, published 9 June 2026.
Which products and versions are affected?: Microsoft Windows All supported versions.
Is there a fix for CVE-2026-45657?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-45657 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-45657?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This vulnerability is classified as a Use-After-Free (CWE-416) and Heap-based Buffer Overflow (CWE-122) within the Windows Kernel. The flaw is triggered when the kernel improperly handles objects in memory, allowing an attacker to send specially crafted network packets to a vulnerable system. Because the vulnerability exists at the kernel level and is reachable over the network without authentication (AV:N/AC:L/PR:N/UI:N), a successful exploit grants the attacker SYSTEM-level privileges. This can lead to full remote code execution (RCE). Microsoft has released security updates to address this issue via the MSRC.

Affected products

Microsoft Windows All supported versions

Timeline

2026-06-09: disclosed
2026-06-09: advisory

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45657

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