Protection mechanism failure in Microsoft Windows and Windows Server - CVE-2026-34348

Vulnerability identifier: #VU137957

CSH Severity: Low

CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-34348

CWE-ID: CWE-693

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote user to disclose sensitive information.

The vulnerability exists due to protection mechanism failure in Windows Event Logging Service when handling network requests. A remote user can send crafted requests to disclose sensitive information.

The disclosed information is limited to small portions of heap memory.

Microsoft Windows
Windows Server

Install security update from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7548, 10 22H2 10.0.19045.7548, 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 10.0.28000.2113, 11 26H1 10.0.28000.2269, 11 26H1 10.0.28000.2525
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-34348

• Multiple vulnerabilities in Microsoft Windows