CVE-2026-40378: CWE-789: Memory Allocation with Excessive Size Value in Microsoft Windows 10 Version 1607
Memory allocation with excessive size value in Windows Local Security Authority Subsystem Service (LSASS) allows an unauthorized attacker to deny service over a network.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-40378) affects Windows 10 Version 1607 (build 10.0.14393.0) and is classified under CWE-789: Memory Allocation with Excessive Size Value. The issue occurs in the LSASS component, where improper handling of memory allocation requests with excessive size values can be exploited by an unauthenticated attacker remotely to cause a denial of service condition. The CVSS v3.1 base score is 7.5, indicating high severity, with network attack vector, low attack complexity, no privileges or user interaction required, and impact limited to availability (denial of service). Microsoft has published an official fix for this vulnerability.
Potential Impact
An attacker can remotely trigger a denial of service by exploiting the memory allocation flaw in LSASS, causing the affected system to become unavailable. There is no impact on confidentiality or integrity. No known exploits are reported in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40378 to remediate this vulnerability.
CVE-2026-40378: CWE-789: Memory Allocation with Excessive Size Value in Microsoft Windows 10 Version 1607
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.
CVSS v3.1
Score 7.5high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-40378) affects Windows 10 Version 1607 (build 10.0.14393.0) and is classified under CWE-789: Memory Allocation with Excessive Size Value. The issue occurs in the LSASS component, where improper handling of memory allocation requests with excessive size values can be exploited by an unauthenticated attacker remotely to cause a denial of service condition. The CVSS v3.1 base score is 7.5, indicating high severity, with network attack vector, low attack complexity, no privileges or user interaction required, and impact limited to availability (denial of service). Microsoft has published an official fix for this vulnerability.
Potential Impact
An attacker can remotely trigger a denial of service by exploiting the memory allocation flaw in LSASS, causing the affected system to become unavailable. There is no impact on confidentiality or integrity. No known exploits are reported in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40378 to remediate this vulnerability.
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: 08/13/2026, 14:14:06 UTC
Last updated: 08/28/2026, 19:39:44 UTC
Views: 90
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