Cyber Resilience

CVE-2025-21221

High

Published: 08 April 2025

Published
08 April 2025
Modified
10 July 2025
KEV Added
Patch
CVSS Score v3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.0174 82.9th percentile
Risk Priority 19 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-21221 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows Server 2008. Its CVSS base score is 8.8 (High).

Operationally, ranked in the top 17.1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis

CVE-2025-21221 is a heap-based buffer overflow vulnerability, tracked under CWE-122, that affects the Windows Telephony Service. The flaw carries a CVSS 3.1 base score of 8.8 and permits remote code execution when triggered over a network.

An unauthorized attacker can exploit the issue remotely without authentication, though user interaction is required. Successful exploitation grants the attacker the ability to execute arbitrary code with high impact on confidentiality, integrity, and availability.

The single reference points to the Microsoft Security Response Center advisory for CVE-2025-21221, which is the authoritative source for official mitigation guidance and patch availability. The associated EPSS score remains low, with a current value of 0.0174 and a peak of 0.0205.

EU & UK References

Vulnerability details

Heap-based buffer overflow in Windows Telephony Service allows an unauthorized attacker to execute code over a network.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

microsoft
windows 10 1507
≤ 10.0.10240.20978 · ≤ 10.0.10240.20978
microsoft
windows 10 1607
≤ 10.0.14393.7969 · ≤ 10.0.14393.7969
microsoft
windows 10 1809
≤ 10.0.17763.7136 · ≤ 10.0.17763.7136
microsoft
windows 10 21h2
≤ 10.0.19044.5737
microsoft
windows 10 22h2
≤ 10.0.19045.5737
microsoft
windows 11 22h2
≤ 10.0.22621.5189
microsoft
windows 11 23h2
≤ 10.0.22631.5189
microsoft
windows 11 24h2
≤ 10.0.26100.3775
microsoft
windows server 2008
all versions, r2
microsoft
windows server 2012
all versions, r2
+5 more product configuration(s) — see NVD for full list

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References