Summary
Impact: Remote Code Execution. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
According to the CVSS metric, the attack vector is network (AV:N) and the user interaction is required (UI:R). What is the target context of the remote code execution?
This attack requires a client to connect to a malicious server, and that could allow the attacker to gain code execution on the client.
Are the updates for Windows 10 for x64-based Systems and Windows 10 for 32-bit Systems currently available?
Yes. As of April 9, 2025, the security update (5055547) for Windows 10 for x64-based Systems and Windows 10 for 32-bit Systems are available. Customers running Windows 10 should ensure the update is installed to be protected from this vulnerability.
Security updates
10.0.17763.7136 — https://support.microsoft.com/help/5055519
10.0.20348.3453 — https://support.microsoft.com/help/5055526
10.0.19044.5737 — https://support.microsoft.com/help/5055518
10.0.22621.5189 — https://support.microsoft.com/help/5055528
10.0.26100.3775 — https://support.microsoft.com/help/5055523
10.0.25398.1551 — https://support.microsoft.com/help/5055527
10.0.10240.20978 — https://support.microsoft.com/help/5055547
10.0.14393.7969 — https://support.microsoft.com/help/5055521
6.0.6003.23220 — https://support.microsoft.com/help/5055609
6.0.6003.23220 — https://support.microsoft.com/help/5055596
6.1.7601.27670 — https://support.microsoft.com/help/5055561
6.1.7601.27670 — https://support.microsoft.com/help/5055570
6.2.9200.25423 — https://support.microsoft.com/help/5055581
6.3.9600.22523 — https://support.microsoft.com/help/5055557
Vulnerabilities 1
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High 8.8
Windows Telephony Service Remote Code Execution Vulnerability
Heap-based buffer overflow in Windows Telephony Service allows an unauthorized attacker to execute code over a network.
Revision history
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#2
The security updates for Windows 10 for 32-bit Systems and Windows 10 for x64-based Systems are now available. See the Security Updates table for more information.
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#1
Information published.
References
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CVE-2025-21205 Windows Telephony Service Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21205
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss