Out-of-bounds read in Microsoft Windows and Windows Server - CVE-2026-35423

Vulnerability identifier: #VU131254

CSH Severity: Medium

CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-35423

CWE-ID: CWE-125

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition in Windows 11 Telnet Client. A remote attacker can trick a victim to initiate a Telnet connection to a malicious or compromised server, trigger an out-of-bounds read error and read contents of memory on the system or perform a denial of service (DoS) condition.

Microsoft Windows
Windows Server

Install updates from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7291, 10 22H2 10.0.19045.7291, 10 1607 10.0.14393.9140, 10 1809 10.0.17763.8755, 11 23H2 10.0.22631.7079, 11 24H2 10.0.26100.8390, 11 24H2 10.0.26100.8457, 11 25H2 10.0.26200.8390, 11 25H2 10.0.26200.8457, 11 26H1 10.0.28000.2113
Windows Server - addressed in versions 2012 R2 6.3.9600.23181, 2012 6.2.9200.26079, 2016 10.0.14393.9140, 2019 10.0.17763.8755, 2022 23H2 10.0.25398.2330, 2022 10.0.20348.5074, 2022 10.0.20348.5139, 2025 10.0.26100.32772, 2025 10.0.26100.32860

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-35423

• Out-of-bounds read in Microsoft Windows 11 Telnet Client