CVE-2026-40378: CWE-789: Memory Allocation with Excessive Size Value in Microsoft Windows 10 Version 1607
CVE-2026-40378 is a high-severity vulnerability in Microsoft Windows 10 Version 1607 where the Local Security Authority Subsystem Service (LSASS) improperly handles memory allocation with an excessive size value. This flaw allows an unauthorized attacker to cause a denial of service over a network. An official fix is available from Microsoft to address this issue.
AI Analysis
Technical Summary
This vulnerability involves a memory allocation with an excessive size value in the Windows LSASS component on Windows 10 Version 1607 (build 10.0.14393.0). Exploitation can lead to denial of service (DoS) without requiring user interaction or privileges. The CVSS 3.1 base score is 7.5, reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability. Microsoft has released an official fix for this vulnerability as detailed in their security update guide.
Potential Impact
An attacker can exploit this vulnerability remotely to cause a denial of service condition on affected Windows 10 Version 1607 systems by triggering excessive memory allocation in LSASS. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Apply the official security update provided by Microsoft as referenced in their advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40378) to remediate this vulnerability. Since an official fix is available, deploying the patch is the recommended mitigation.
CVE-2026-40378: CWE-789: Memory Allocation with Excessive Size Value in Microsoft Windows 10 Version 1607
Description
CVE-2026-40378 is a high-severity vulnerability in Microsoft Windows 10 Version 1607 where the Local Security Authority Subsystem Service (LSASS) improperly handles memory allocation with an excessive size value. This flaw allows an unauthorized attacker to cause a denial of service over a network. An official fix is available from Microsoft to address this issue.
CVSS v3.1
Score 7.5high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves a memory allocation with an excessive size value in the Windows LSASS component on Windows 10 Version 1607 (build 10.0.14393.0). Exploitation can lead to denial of service (DoS) without requiring user interaction or privileges. The CVSS 3.1 base score is 7.5, reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability. Microsoft has released an official fix for this vulnerability as detailed in their security update guide.
Potential Impact
An attacker can exploit this vulnerability remotely to cause a denial of service condition on affected Windows 10 Version 1607 systems by triggering excessive memory allocation in LSASS. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Apply the official security update provided by Microsoft as referenced in their advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40378) to remediate this vulnerability. Since an official fix is available, deploying the patch is the recommended mitigation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-04-11T23:06:15.615Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40378","vendor":"Microsoft"}]
Threat ID: 6a566f6768715ace43e6b2fc
Added to database: 07/14/2026, 17:18:31 UTC
Last enriched: 07/15/2026, 02:04:28 UTC
Last updated: 07/15/2026, 02:04:28 UTC
Views: 3
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