CVE-2025-21339
Published: 14 January 2025
Summary
CVE-2025-21339 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
CVE-2025-21339 is a remote code execution vulnerability in the Windows Telephony Service, assigned CWE-122 and carrying a CVSS 3.1 score of 8.8. The flaw affects the telephony component within Windows and permits an attacker to execute arbitrary code on a vulnerable system.
Exploitation requires network access with low attack complexity and no privileges, though user interaction is needed. Successful exploitation can result in full compromise of confidentiality, integrity, and availability on the target system.
The official Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21339 contains guidance on available patches and mitigation steps. The associated EPSS score has remained flat at 0.0806 with no material increase since disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-2404
Vulnerability details
Windows Telephony Service Remote Code Execution Vulnerability
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The CVE describes a remote code execution vulnerability in the Windows Telephony Service triggered by user interaction with malicious files or network resources, directly mapping to exploitation for client execution.
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-2 requires timely remediation of flaws, directly addressing the heap-based buffer overflow in Windows Telephony Service by mandating patch application as recommended by Microsoft.
SI-16 implements memory protections such as ASLR and DEP that comprehensively mitigate heap-based buffer overflow exploits leading to remote code execution.
SI-10 enforces input validation to prevent buffer overflows in the Windows Telephony Service when processing malicious files or network resources.