Heap-based buffer overflow in Microsoft Windows and Windows Server - CVE-2026-59134

Vulnerability identifier: #VU141743

CSH Severity: Medium

CVSS v4: 7.5 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-59134

CWE-ID: CWE-122

Exploitation vector: Remote access

Exploit availability: No public exploit available

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 Remote Desktop Protocol content over a network. A remote attacker can send specially crafted protocol data to execute arbitrary code.

User interaction is required, and successful exploitation depends on specific protocol settings or configurations being in place.

Microsoft Windows
Windows Server

Install security update from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7663, 10 22H2 10.0.19045.7663, 10 1607 10.0.14393.9418, 10 1809 10.0.17763.9115, 11 23H2 10.0.22631.7517, 11 24H2 10.0.26100.9106, 11 24H2 10.0.26100.9168, 11 25H2 10.0.26200.9168, 11 26H1 10.0.28000.2704
Windows Server - addressed in versions 2012 R2 6.3.9600.23337, 2012 6.2.9200.26279, 2016 10.0.14393.9418, 2019 10.0.17763.9115, 2022 10.0.20348.5440, 2022 10.0.20348.5499, 2025 10.0.26100.33222, 2025 10.0.26100.33296

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-59134
• https://support.microsoft.com/help/5120238

• Multiple vulnerabilities in Microsoft Windows