Raw vector
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-20931 is a high-severity External Control of File Name or Path (CWE-73) vulnerability in Microsoft Windows Server 2008. Its CVSS base score is 8.0 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked in the top 47% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-20931 is an external control of file name or path vulnerability, tracked under CWE-73, that affects the Windows Telephony Service. The flaw carries a CVSS 3.1 score of 8.0 and permits an attacker to manipulate file paths or names, resulting in privilege elevation on the affected Windows component.
An authorized attacker positioned on an adjacent network can exploit the issue without user interaction. Successful exploitation grants the attacker high impact on confidentiality, integrity, and availability by elevating privileges on the target system.
Microsoft’s advisory at msrc.microsoft.com details the vulnerability and available updates, while Vicarius has published accompanying detection and mitigation scripts that practitioners can use to identify and remediate affected systems.
EPSS for the CVE rose from a low baseline to a peak of 0.0222 on 2026-02-14 before receding to the current value of 0.0044, indicating a temporary increase in exploitation interest after disclosure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2123
Vulnerability Data
External control of file name or path in Windows Telephony Service allows an authorized attacker to elevate privileges over an adjacent network.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V5.3.2
Mitigating Controls (NIST 800-53 r5) AI
Input validation directly rejects or sanitizes untrusted path strings before they reach filesystem operations.
Enforces authorization checks on the actual resource accessed, blocking unauthorized files even when a malicious path is supplied.
Least-privilege limits the set of files or directories any subject can affect, shrinking the blast radius of a path-control flaw.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect path-traversal issues but does not itself implement preventive controls.
Secure development lifecycle mandates input validation and path-handling controls that directly prevent external file/path manipulation.
Application security requirements explicitly call for controls against untrusted input influencing file operations.
Secure architecture principles discourage unsafe path construction but do not prescribe concrete file-name controls.
Secure coding standards require canonicalization, allow-listing, and bounds checks on file paths, directly eliminating CWE-73.
Information access restriction limits which files can be reached, indirectly reducing impact of path manipulation.