Cleartext transmission of sensitive information in Microsoft Windows and Windows Server - CVE-2026-34346

Vulnerability identifier: #VU137881

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-34346

CWE-ID: CWE-319

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to software uses insecure communication channel to transmit sensitive information in Windows Ancillary Function Driver for WinSock. A local user can gain access to sensitive data.

Microsoft Windows
Windows Server

Install updates from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7548, 10 22H2 10.0.19045.7548, 10 1607 10.0.14393.9339, 10 1809 10.0.17763.9020, 11 23H2 10.0.22631.7376, 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, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34346

• Multiple vulnerabilities in Microsoft Windows Ancillary Function Driver for WinSock