CVE-2025-21409
Published: 14 January 2025
Summary
CVE-2025-21409 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows 10 1507. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 7.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
The vulnerability CVE-2025-21409 is a remote code execution flaw in the Windows Telephony Service, carrying a CVSS 3.1 base score of 8.8 and classified under CWE-122. It affects the Telephony Service component on Windows systems and was publicly disclosed on 14 January 2025.
An unauthenticated attacker can trigger the flaw over the network with low attack complexity and only user interaction required, resulting in full compromise of confidentiality, integrity, and availability on the target system under an unchanged scope.
Microsoft has published an advisory and patch information for the issue at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21409.
The associated EPSS score has remained flat at 0.0806 with no material increase since disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-2469
Vulnerability details
Windows Telephony Service Remote Code Execution Vulnerability
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The RCE vulnerability in the Windows Telephony Service requires user interaction (e.g., malicious link or file) for remote exploitation leading to arbitrary code execution, directly mapping to Exploitation for Client Execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly remediates the heap-based buffer overflow in Windows Telephony Service by requiring timely application of Microsoft's security patch.
Implements memory protections like ASLR, DEP, and heap isolation to prevent arbitrary code execution from heap buffer overflows.
Requires validation of network inputs to the Telephony Service to block malformed data triggering the buffer overflow.