Use-after-free in Microsoft Windows and Windows Server - CVE-2025-21406

Vulnerability identifier: #VU103786

CSH Severity: High

CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2025-21406

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in Windows Telephony Service. A remote attacker can trick a victim to connect to a malicious server and execute arbitrary code on the target system.

Microsoft Windows
Windows Server

Install updates from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.5487, 10 22H2 10.0.19045.5487, 10 1507 10.0.10240.20915, 10 1607 10.0.14393.7785, 10 1809 10.0.17763.6893, 11 22H2 10.0.22621.4890, 11 23H2 10.0.22631.4890, 11 24H2 10.0.26100.3107
Windows Server - addressed in versions 2008 R2 6.1.7601.27566, 2008 6.0.6003.23117, 2012 R2 6.3.9600.22417, 2012 6.2.9200.25317, 2016 10.0.14393.7785, 2022 23H2 10.0.25398.1425, 2022 10.0.20348.3148, 2022 10.0.20348.3207, 2025 10.0.26100.3107, 2025 10.0.26100.3194

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21406

• Multiple vulnerabilities in Microsoft Windows Telephony Service