CVE-2026-40378 Details
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.
A denial-of-service vulnerability has been identified in the Windows Local Security Authority Subsystem Service (LSASS). This issue arises from memory allocation that allows excessive size values, enabling an unauthorized attacker to disrupt service over the network. The vulnerability affects multiple Windows versions, including Windows Server 2012 R2, Windows Server 2012, Windows Server 2016, Windows Server 2025, Windows 10 (various versions), Windows 11 (various versions), and Windows Server 2022.
Users can apply the security update for this vulnerability, which is available through the Microsoft Update Catalog. Specific update details can be found in the Microsoft Knowledge Base articles KB5099444, KB5099445, KB5099535, KB5099536, KB5095051, KB5101650, KB5099414, KB5099539, KB5099540, and KB5099538.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 14, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40378 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-789 | Memory Allocation with Excessive Size Value | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| microsoft windows 10 1607 | < 10.0.14393.9339 |
CPE
Remediation
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| microsoft windows 10 1809 | < 10.0.17763.9020 |
CPE
Remediation
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| microsoft windows 10 21h2 | < 10.0.19044.7548 |
CPE
Remediation
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| microsoft windows 10 22h2 | < 10.0.19045.7548 |
CPE
Remediation
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| microsoft windows 11 23h2 | < 10.0.22631.7376 |
CPE
Remediation
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| microsoft windows 11 24h2 | < 10.0.26100.8875 |
CPE
Remediation
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| microsoft windows 11 25h2 | < 10.0.26200.8875 |
CPE
Remediation
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| microsoft windows 11 26h1 | < 10.0.28000.2269 |
CPE
Remediation
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| microsoft windows server 2012 | r2 |
CPE
Remediation
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| microsoft windows server 2016 | < 10.0.14393.9339 |
CPE
Remediation
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| microsoft windows server 2019 | < 10.0.17763.9020 |
CPE
Remediation
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| microsoft windows server 2022 | < 10.0.20348.5386 |
CPE
Remediation
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| microsoft windows server 2025 | < 10.0.26100.33158 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 22, 2026 | CVE Modified | [email protected] |
| Jul 16, 2026 | Initial Analysis | [email protected] |
| Jul 14, 2026 | CVE Modified | CISA-ADP |
| Jul 14, 2026 | New CVE Received | [email protected] |