Heap-based Buffer Overflow in Windows Win32K Component
CVE-2026-40403

8.8HIGH

Key Information:

Vendor

Microsoft
Status
Windows 10 Version 1607
Windows 10 Version 1809
Windows 10 Version 21h2
Windows 10 Version 22h2
Vendor
CVE Published:
12 May 2026

What is CVE-2026-40403?

A heap-based buffer overflow vulnerability exists in the Windows Win32K graphics component. An authorized attacker, utilizing this flaw, is capable of executing arbitrary code locally. This exposure results from improper validation of user-provided data in memory. Successful exploitation could allow the attacker to manipulate system operations and potentially compromise the integrity and availability of the affected systems.

Affected Version(s)

Windows 10 Version 1607 32-bit Systems 10.0.14393.0 < 10.0.14393.9140

Windows 10 Version 1809 32-bit Systems 10.0.17763.0 < 10.0.17763.8755

Windows 10 Version 21H2 32-bit Systems 10.0.19044.0 < 10.0.19044.7291

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.