Heap-based buffer overflow in Microsoft Windows and Windows Server - CVE-2026-54990
Published: July 17, 2026
Vulnerability identifier: #VU137934
CSH Severity: High
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-54990
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to heap-based buffer overflow in Remote Desktop Client when handling responses from a malicious RDP server. A remote attacker can send specially crafted responses to execute arbitrary code.
User interaction is required to establish a connection to a malicious RDP server.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-54990
Install security update from vendor's website.
Microsoft Windows - addressed in versions 11 24H2 10.0.26100.8875, 11 25H2 10.0.26200.8875, 11 26H1 10.0.28000.2269, 11 26H1 10.0.28000.2525
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2025 10.0.26100.33158
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2025 10.0.26100.33158