CVE-2026-83906: Windows Shell authentication algorithm spoofing

CVE-2026-83906 · Severity: medium · CVSS 6.5 · Published 2026-10-13

Windows Shell, which handles user authentication and system operations, contains a flaw in its authentication algorithm that allows an attacker to impersonate legitimate users or systems over a network. An attacker could use this to gain unauthorized access to systems or perform actions as another user without proper credentials.

Technologies: Microsoft Windows Shell, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows 11 26h2, Microsoft Windows Server 2025. Vendors: Microsoft.

Quick answers

Is CVE-2026-83906 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-83906 being exploited in the wild.
How severe is CVE-2026-83906?
Medium severity, with a CVSS score of 6.5, published 13 October 2026.
Which products and versions are affected?
Microsoft Windows Shell.
Is there a fix for CVE-2026-83906?
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-2026-83906 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2026-83906?
Check whether you run Microsoft Windows Shell, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2 or one of the others listed. 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

The vulnerability stems from incorrect implementation of an authentication algorithm in Windows Shell, enabling network-based spoofing attacks. An attacker with network access can exploit this flaw to impersonate other users or systems. The vulnerability has not been observed in active exploitation at this time.

Affected products

  • Microsoft Windows Shell

Timeline

  • 2026-10-13: disclosed

References

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