Memory Allocation Vulnerability in Windows LSASS Affects Microsoft Products
CVE-2026-40378

7.5HIGH

Key Information:

Vendor

Microsoft
Status
Windows 10 Version 1607
Windows 10 Version 1809
Windows 10 Version 21h2
Windows 10 Version 22h2
Vendor
CVE Published:
14 July 2026

What is CVE-2026-40378?

A memory allocation vulnerability in the Windows Local Security Authority Subsystem Service (LSASS) can be exploited by attackers, allowing them to allocate excessive memory size values. This can lead to a denial of service condition over a network, compromising system availability and stability. Microsoft has issued guidance and patches to mitigate this vulnerability, urging users to update their systems immediately to safeguard against potential exploits.

Affected Version(s)

Windows 10 Version 1607 32-bit Systems 10.0.14393.0 < 10.0.14393.9339

Windows 10 Version 1809 32-bit Systems 10.0.17763.0 < 10.0.17763.9020

Windows 10 Version 21H2 32-bit Systems 10.0.19044.0 < 10.0.19044.7548

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.