CVE-2026-40378

Windows Local Security Authority Subsystem Service (LSASS) Denial of Service Vulnerability

State: Published
Severity: 7.5 High
Published: Jul 14, 2026
Updated: Nov 1, 2026
Reserved: Apr 11, 2026

Description

Memory allocation with excessive size value in Windows Local Security Authority Subsystem Service (LSASS) allows an unauthorized attacker to deny service over a network.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-789 Memory Allocation with Excessive Size Value

Affected Products

Product	Versions
Windows 10 Version 1607Microsoft	10.0.14393.0 to before 10.0.14393.9339Affected
Windows 10 Version 1809Microsoft	10.0.17763.0 to before 10.0.17763.9020Affected
Windows 10 Version 21H2Microsoft	10.0.19044.0 to before 10.0.19044.7548Affected
Windows 10 Version 22H2Microsoft	10.0.19045.0 to before 10.0.19045.7548Affected
Windows 11 version 23H2Microsoft	10.0.22631.0 to before 10.0.22631.7376Affected
Windows 11 Version 23H2Microsoft	10.0.22631.0 to before 10.0.22631.7376Affected
Windows 11 Version 24H2Microsoft	10.0.26100.0 to before 10.0.26100.8875Affected
Windows 11 Version 25H2Microsoft	10.0.26200.0 to before 10.0.26200.8875Affected
Windows 11 version 26H1Microsoft	10.0.28000.0 to before 10.0.28000.2525Affected
Windows Server 2012Microsoft	6.2.9200.0 to before 6.2.9200.26226Affected
Windows Server 2012 (Server Core installation)Microsoft	6.2.9200.0 to before 6.2.9200.26226Affected
Windows Server 2012 R2Microsoft	6.3.9600.0 to before 6.3.9600.23291Affected
Windows Server 2012 R2 (Server Core installation)Microsoft	6.3.9600.0 to before 6.3.9600.23291Affected
Windows Server 2016Microsoft	10.0.14393.0 to before 10.0.14393.9339Affected
Windows Server 2016 (Server Core installation)Microsoft	10.0.14393.0 to before 10.0.14393.9339Affected
Windows Server 2019Microsoft	10.0.17763.0 to before 10.0.17763.9020Affected
Windows Server 2019 (Server Core installation)Microsoft	10.0.17763.0 to before 10.0.17763.9020Affected
Windows Server 2022Microsoft	10.0.20348.0 to before 10.0.20348.5386Affected
Windows Server 2025Microsoft	10.0.26100.0 to before 10.0.26100.33158Affected
Windows Server 2025 (Server Core installation)Microsoft	10.0.26100.0 to before 10.0.26100.33158Affected

References

Windows Local Security Authority Subsystem Service (LSASS) Denial of Service Vulnerabilityvendor-advisorypatch

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