Remote code execution in Microsoft Windows Telephony Server

1) Double free

EUVDB-ID: #VU103794

Risk: High

CVSSv4.0: 6.1 [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/E:U/U:Amber]

CVE-ID: CVE-2025-21201

CWE-ID: CWE-415 - Double Free

Exploit availability: No

Description

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

The vulnerability exists due to a boundary error in Windows Telephony Server. A remote attacker can trick a victim to connect to a malicious server, trigger double free error and execute arbitrary code on the target system.

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

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 11 24H2 10.0.26100.2894

Windows Server: 2008 R2 SP1 - 2025 10.0.26100.2894

CPE2.3

• cpe:2.3:o:microsoft:windows:10_21H2:10.0.19044.5371:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_22H2:10.0.19045.5371:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1507:10.0.10240.20890:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1607:10.0.14393.7699:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1809:10.0.17763.6775:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:11_22H2:10.0.22621.4751:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:11_23H2:10.0.22631.4751:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:11_24H2:10.0.26100.2894:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server:2008:6.0.6003.23070:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server:2012:6.2.9200.25273:*:*:*:*:*:*

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21201

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.