Vulnerability in Microsoft Windows 10 Version 1607
CVE-2026-40378
Memory allocation with excessive size value in Windows Local Security Authority Subsystem Service (LSASS) allows an unauthorized attacker to deny service over a network.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Microsoft Windows 10 Version 1607 — versions 10.0.14393.0
- Microsoft Windows 10 Version 1809 — versions 10.0.17763.0
- Microsoft Windows 10 Version 21h2 — versions 10.0.19044.0
- Microsoft Windows 10 Version 22h2 — versions 10.0.19045.0
- Microsoft Windows 11 Version 23h2 — versions 10.0.22631.0
- Microsoft Windows 11 Version 24h2 — versions 10.0.26100.0
- Microsoft Windows 11 Version 25h2 — versions 10.0.26200.0
- Microsoft Windows 11 Version 26h1 — versions 10.0.28000.0
- Microsoft Windows Server 2012 — versions 6.2.9200.0
- Microsoft Windows Server 2012 R2 — versions 6.3.9600.0
Weakness classification (CWE)
References
- secure@microsoft.com (vendor-advisory, patch)
Frequently asked questions
- What is CVE-2026-40378?
- CVE-2026-40378 is a high-severity vulnerability in Microsoft Windows 10 Version 1607, classified under CWE-789. CVSS score: 7.5/10. Published 2026-07-14.
- How severe is CVE-2026-40378?
- High severity. CVSS v3 base score is 7.5 out of 10.