Integer overflow in Microsoft Windows and Windows Server - CVE-2025-21243

Vulnerability identifier: #VU102609

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-2025-21243

CWE-ID: CWE-190

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to integer overflow in Windows Telephony Service. A remote attacker can pass specially crafted data to the application, trigger integer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Microsoft Windows
Windows Server

Install updates from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.5371, 10 22H2 10.0.19045.5371, 10 1507 10.0.10240.20890, 10 1607 10.0.14393.7699, 10 1809 10.0.17763.6775, 11 22H2 10.0.22621.4751, 11 23H2 10.0.22631.4751, 11 24H2 10.0.26100.3107
Windows Server - addressed in versions 2008 R2 6.1.7601.27520, 2008 6.0.6003.23070, 2012 R2 6.3.9600.22371, 2012 6.2.9200.25273, 2016 10.0.14393.7785, 2022 23H2 10.0.25398.1369, 2022 10.0.20348.3091, 2025 10.0.26100.2894

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21243

• Multiple vulnerabilities in Microsoft Windows Telephony Service