CVE-2026-40408: Windows WAN ARP Driver Elevation of Privilege Vulnerability
Use after free in Windows Kernel-Mode Drivers allows an authorized attacker to elevate privileges locally.
Other sources
Windows WAN ARP Driver Elevation of Privilege Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.17763.8755Patch KB5087538 - Upgrade
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Fixed in 6.3.9600.23181Patch KB5087471 - Upgrade
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Fixed in 10.0.20348.5139Fixed in 10.0.20348.5074Patch KB5087424 - Upgrade
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Fixed in 10.0.14393.9140Patch KB5087537 - Upgrade
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Fixed in 6.2.9200.26079Patch KB5087470 - Upgrade
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Fixed in 10.0.28000.2113Patch KB5089548 - Upgrade
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Fixed in 10.0.22631.7219Patch KB5093998 - Upgrade
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Fixed in 10.0.25398.2330Patch KB5087541 - Upgrade
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Fixed in 10.0.26100.8457Fixed in 10.0.26100.8390Patch KB5089466 - Upgrade
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Fixed in 10.0.26200.8457Fixed in 10.0.26200.8390Patch KB5089466 - Upgrade
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Fixed in 10.0.26100.32860Fixed in 10.0.26100.32772Patch KB5087423 - Upgrade
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Fixed in 10.0.22631.7079Patch KB5087420 - Upgrade
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Fixed in 10.0.19045.7417Patch KB5094127 - Upgrade
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Fixed in 10.0.19044.7291Patch KB5087544
Event History
Frequently Asked Questions
What is the severity of CVE-2026-40408?
CVE-2026-40408 has been classified as a critical elevation of privilege vulnerability.
How do I fix CVE-2026-40408?
You can fix CVE-2026-40408 by applying the relevant security patches provided by Microsoft.
What systems are affected by CVE-2026-40408?
CVE-2026-40408 affects multiple versions of Windows, including Windows 10, Windows Server 2019, Windows Server 2022, and Windows 11.
What is the impact of CVE-2026-40408 on my system?
The impact of CVE-2026-40408 is that an authorized attacker could exploit the vulnerability to elevate privileges on the affected system.
Is there a mitigation for CVE-2026-40408 if I can't apply the patch immediately?
The best mitigation while waiting for a patch is to limit user permissions and monitor for suspicious activity on affected systems.