#VU103794 Double free in Windows and Windows Server - CVE-2025-21201

Vulnerability identifier: #VU103794

Vulnerability 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

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Windows
Operating systems & Components / Operating system
Windows Server
Operating systems & Components / Operating system

Vendor: Microsoft

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: before 10 21H2, 10 22H2, 10 1507, 10 1607, 10 1809, 11 22H2, 11 23H2, 11 24H2, 10 21H2, 10 21H2, 10 21H2, 10 21H2, 10 21H2, 10 21H2, 10 21H2, 10 21H2

Windows Server: before 2008 R2, 2008, 2012 R2, 2012, 2016, 2022 23H2, 2022, 2025, 2008 R2, 2008 R2, 2008 R2, 2008 R2, 2008 R2

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

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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.