CVE-2026-73025: Windows iSCSI Security Feature Bypass Vulnerability

Overview

Severity

Critical (CVSS 9.8)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Category

Security Feature Bypass

Exploit Status

Not Exploited

Exploitation Likelihood

Unlikely

Patch Tuesday

2026-Sep

Released

2026-09-08

Description

Weak authentication in Windows iSCSI allows an unauthorized attacker to bypass a security feature over a network.

FAQ

What kind of security feature could be bypassed by successfully exploiting this vulnerability? The authentication feature could be bypassed as this vulnerability allows impersonation. How could an attacker exploit this vulnerability? An unauthenticated attacker could connect over the network to an affected iSCSI Target Server and send specially crafted authentication data. Successful exploitation could bypass CHAP authentication and allow unauthorized access to mapped storage. User interaction is not required.

Affected Products (16)

Windows

• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows Server 2025 (Server Core installation)
• Windows Server 2025
• Windows 10 Version 1607 for 32-bit Systems
• Windows 10 Version 1607 for x64-based Systems
• Windows Server 2016
• Windows Server 2016 (Server Core installation)

ESU

• Windows Server 2012
• Windows Server 2012 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 R2 (Server Core installation)

Security Updates (6)

• 5122876
• 5122882
• 5122871
• 5123099
• 5123065
• 5123066

Acknowledgments

<a href="https://www.linkedin.com/in/david-c-826599a4/">David Carliez</a> with DC CyberSecurity

Revision History

• 2026-09-08: Information published.