CVE-2026-40403: Windows Graphics Component Remote Code Execution Vulnerability

Overview

Severity

High (CVSS 8.8)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C

Category

Remote Code Execution

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-May

Released

2026-05-12

Description

Heap-based buffer overflow in Windows Win32K - GRFX allows an authorized attacker to execute code locally.

FAQ

According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability? This vulnerability could lead to a contained execution environment escape. Please refer to AppContainer Isolation for more information. According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution? The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. The vulnerable endpoint is only available over the local VM interface as all external communication is blocked. This means an attacker needs to execute code from the local machine to exploit the vulnerability. According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability? Any authenticated attacker could trigger this vulnerability. It does not require admin or other elevated privileges. How could an attacker exploit this vulnerability? An attacker can exploit this vulnerability by getting access to the local guest VM so they can attack the Host OS.

Affected Products (31)

Windows

• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows 10 Version 21H2 for 32-bit Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 23H2 for x64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows 11 Version 24H2 for x64-based Systems
• Windows Server 2025
• Windows 11 version 26H1 for x64-based Systems
• Windows 11 Version 26H1 for ARM64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows 10 Version 1607 for x64-based Systems
• Windows Server 2016
• Windows Server 2016 (Server Core installation)

ESU

• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for 32-bit Systems
• Windows Server 2012
• Windows Server 2012 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 R2 (Server Core installation)

Security Updates (14)

• 5087538
• 5087545
• 5087424
• 5087544
• 5087539
• 5087423
• 5089549
• 5089466
• 5087420
• 5087541
• 5089548
• 5087537
• 5087470
• 5087471

Acknowledgments

Calif.io and Milad Nasr (Anthropic) with Claude with Calif.io and Anthropic

Revision History

• 2026-05-12: Information published.