CVE-2026-40415: Windows TCP/IP Remote Code Execution Vulnerability

Overview

Severity
High (CVSS 8.1)
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
Unlikely
Patch Tuesday
2026-May
Released
2026-05-12

Description

Use after free in Windows TCP/IP allows an unauthorized attacker to execute code over a network.

FAQ

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation requires the target system to be under sustained low-memory (memory pressure) conditions, which are not commonly present in normal operation. This makes the vulnerability difficult to reliably trigger, as the attacker must first induce or wait for a constrained memory state before exploitation becomes possible. How could an attacker exploit this vulnerability? An attacker could exploit this vulnerability by sending specially crafted malicious traffic to a vulnerable server.

Affected Products (23)

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

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

Security Updates (11)

Acknowledgments

Windows Attack Research &amp; Protection (WARP) with <a href="https://microsoft.com/">Microsoft</a>

Revision History

  • 2026-05-12: Information published.