Cyber Posture

CVE-2025-21266

High

Published: 14 January 2025

Published
14 January 2025
Modified
27 January 2025
KEV Added
Patch
CVSS Score 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.0165 82.2th percentile
Risk Priority 19 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-21266 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 17.8% 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-2 (Flaw Remediation) and CM-7 (Least Functionality).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploitation for Client Execution (T1203). What defenders deploy: see the NIST 800-53 controls recommended below.
Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

prevent

Directly remediates the Windows Telephony Service RCE vulnerability (CVE-2025-21266) by applying vendor patches as specified in the MSRC advisory.

prevent

Implements memory protections like ASLR and DEP to mitigate stack-based buffer overflow (CWE-122) exploitation leading to RCE in the service.

prevent

Restricts the system to least functionality by disabling the non-essential Windows Telephony Service, removing the vulnerable attack surface.

MITRE ATT&CK Enterprise TechniquesAI

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
Why these techniques?

RCE vulnerability in Windows service with network vector and explicit user interaction requirement (e.g., malicious link/file) directly enables client-side exploitation for arbitrary code execution.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

Windows Telephony Service Remote Code Execution Vulnerability

Deeper analysisAI

CVE-2025-21266 is a Remote Code Execution Vulnerability in the Windows Telephony Service. Published on 2025-01-14T18:15:45.797, it carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) and is linked to CWE-122, with additional NVD-CWE-noinfo classification.

The vulnerability can be exploited by a remote unauthenticated attacker over the network with low attack complexity, requiring user interaction such as clicking a malicious link or opening a file. Successful exploitation enables high-impact effects on confidentiality, integrity, and availability, allowing arbitrary code execution on the affected Windows system.

Mitigation details are available in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21266.

Details

CWE(s)

Affected Products

microsoft
windows 10 1507
≤ 10.0.10240.20890 · ≤ 10.0.10240.20890
microsoft
windows 10 1607
≤ 10.0.14393.7699 · ≤ 10.0.14393.7699
microsoft
windows 10 1809
≤ 10.0.17763.6775 · ≤ 10.0.17763.6775
microsoft
windows 10 21h2
≤ 10.0.19044.5371
microsoft
windows 10 22h2
≤ 10.0.19045.5371
microsoft
windows 11 22h2
≤ 10.0.22621.4751
microsoft
windows 11 23h2
≤ 10.0.22631.4751
microsoft
windows 11 24h2
≤ 10.0.26100.2894
microsoft
windows server 2008
all versions, r2
microsoft
windows server 2012
all versions, r2
+5 more product configuration(s) — see NVD for full list

CVEs Like This One

CVE-2025-21407Same product: Microsoft Windows 10 1507
CVE-2025-21303Same product: Microsoft Windows 10 1507
CVE-2025-21339Same product: Microsoft Windows 10 1507
CVE-2025-21233Same product: Microsoft Windows 10 1507
CVE-2025-21371Same product: Microsoft Windows 10 1507
CVE-2025-21409Same product: Microsoft Windows 10 1507
CVE-2025-21240Same product: Microsoft Windows 10 1507
CVE-2025-59295Same product: Microsoft Windows 10 1507
CVE-2025-21239Same product: Microsoft Windows 10 1507
CVE-2025-24056Same product: Microsoft Windows 10 1507

References