CVE-2026-42909: Remote Desktop Client Remote Code Execution Vulnerability

Overview

Severity

High (CVSS 7.5)

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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-Jun

Released

2026-06-09

Description

Heap-based buffer overflow in Remote Desktop Client 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 of this vulnerability requires an attacker to win a race condition. How could an attacker exploit this vulnerability? In the case of a Remote Desktop connection, an attacker with control of a Remote Desktop Server could trigger a remote code execution (RCE) on the machine when a victim connects to the attacking server with the vulnerable Remote Desktop Client.

Affected Products (32)

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)
• Remote Desktop client for Windows Desktop
• 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 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)
• Windows App Client for Windows Desktop

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 (12)

• 5094123
• Release Notes
• 5094128
• 5094127
• 5094125
• 5094126
• 5093998
• 5095051
• 5094122
• 5094042
• 5094041
• Security Update

Acknowledgments

pwn2addr

Revision History

• 2026-06-09: Information published.