Insecure Default Variable Initialization in Microsoft Windows and Windows Server - CVE-2026-103577
Published: October 13, 2026
Vulnerability identifier: #VU154318
CSH Severity: Medium
CVSS v4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-103577
CWE-ID: CWE-453
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass authentication and obtain a successful login.
The vulnerability exists due to insecure default variable initialization in Microsoft QUIC when handling authentication over a network. A remote attacker can attempt a remote login to bypass authentication and obtain a successful login.
No user interaction is required. Successful exploitation requires a deep understanding of the system and depends on factors that may include the environment, system configuration, and additional security measures.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-103577
Install security update from vendor's website.
Microsoft Windows - addressed in versions 11 23H2 10.0.22631.7652, 11 24H2 10.0.26100.9711, 11 25H2 10.0.26200.9711, 11 26H1 10.0.28000.3231
Windows Server - addressed in versions 2022 10.0.20348.5761, 2025 10.0.26100.33650
Windows Server - addressed in versions 2022 10.0.20348.5761, 2025 10.0.26100.33650