Windows Telephony Service Elevation of Privilege Vulnerability

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Summary

CVECVE-2026-20931
StatePUBLISHED
Assignermicrosoft
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-13 18:16:20 UTC
Updated2026-05-26 18:16:37 UTC
DescriptionExternal control of file name or path in Windows Telephony Service allows an authorized attacker to elevate privileges over an adjacent network.

Risk And Classification

Primary CVSS: v3.1 8 HIGH from [email protected]

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.003810000 probability, percentile 0.598200000 (date 2026-05-29)

Problem Types: CWE-73 | CWE-73 CWE-73: External Control of File Name or Path

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8HIGHCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS8HIGHCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Microsoft Windows 10 1607 All All All All
Operating System Microsoft Windows 10 1607 All All All All
Operating System Microsoft Windows 10 1809 All All All All
Operating System Microsoft Windows 10 1809 All All All All
Operating System Microsoft Windows 10 21h2 All All All All
Operating System Microsoft Windows 10 22h2 All All All All
Operating System Microsoft Windows 11 23h2 All All All All
Operating System Microsoft Windows 11 24h2 All All All All
Operating System Microsoft Windows 11 25h2 All All All All
Operating System Microsoft Windows Server 2008 - sp2 All All
Operating System Microsoft Windows Server 2008 - sp2 All All
Operating System Microsoft Windows Server 2008 r2 sp1 All All
Operating System Microsoft Windows Server 2012 - All All All
Operating System Microsoft Windows Server 2012 r2 All All All
Operating System Microsoft Windows Server 2016 All All All All
Operating System Microsoft Windows Server 2019 All All All All
Operating System Microsoft Windows Server 2022 All All All All
Operating System Microsoft Windows Server 2022 23h2 All All All All
Operating System Microsoft Windows Server 2025 All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Microsoft Windows 10 Version 1607 affected 10.0.14393.0 10.0.14393.8783 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows 10 Version 1809 affected 10.0.17763.0 10.0.17763.8276 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows 10 Version 21H2 affected 10.0.19044.0 10.0.19044.6809 custom 32-bit Systems, ARM64-based Systems, x64-based Systems
CNA Microsoft Windows 10 Version 22H2 affected 10.0.19045.0 10.0.19045.6809 custom 32-bit Systems, ARM64-based Systems, x64-based Systems
CNA Microsoft Windows 11 Version 22H3 affected 10.0.22631.0 10.0.22631.6491 custom ARM64-based Systems
CNA Microsoft Windows 11 Version 23H2 affected 10.0.22631.0 10.0.22631.6491 custom x64-based Systems
CNA Microsoft Windows 11 Version 24H2 affected 10.0.26100.0 10.0.26100.7623 custom ARM64-based Systems, x64-based Systems
CNA Microsoft Windows 11 Version 25H2 affected 10.0.26200.0 10.0.26200.7623 custom Not specified
CNA Microsoft Windows Server 2008 R2 Service Pack 1 affected 6.1.7601.0 6.1.7601.28117 custom x64-based Systems
CNA Microsoft Windows Server 2008 R2 Service Pack 1 Server Core Installation affected 6.1.7601.0 6.1.7601.28117 custom x64-based Systems
CNA Microsoft Windows Server 2008 Service Pack 2 affected 6.0.6003.0 6.0.6003.23717 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows Server 2008 Service Pack 2 Server Core Installation affected 6.0.6003.0 6.0.6003.23717 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows Server 2012 affected 6.2.9200.0 6.2.9200.25868 custom x64-based Systems
CNA Microsoft Windows Server 2012 Server Core Installation affected 6.2.9200.0 6.2.9200.25868 custom x64-based Systems
CNA Microsoft Windows Server 2012 R2 affected 6.3.9600.0 6.3.9600.22968 custom x64-based Systems
CNA Microsoft Windows Server 2012 R2 Server Core Installation affected 6.3.9600.0 6.3.9600.22968 custom x64-based Systems
CNA Microsoft Windows Server 2016 affected 10.0.14393.0 10.0.14393.8783 custom x64-based Systems
CNA Microsoft Windows Server 2016 Server Core Installation affected 10.0.14393.0 10.0.14393.8783 custom x64-based Systems
CNA Microsoft Windows Server 2019 affected 10.0.17763.0 10.0.17763.8276 custom x64-based Systems
CNA Microsoft Windows Server 2019 Server Core Installation affected 10.0.17763.0 10.0.17763.8276 custom x64-based Systems
CNA Microsoft Windows Server 2022 affected 10.0.20348.0 10.0.20348.4648 custom x64-based Systems
CNA Microsoft Windows Server 2022 23H2 Edition Server Core Installation affected 10.0.25398.0 10.0.25398.2092 custom x64-based Systems
CNA Microsoft Windows Server 2025 affected 10.0.26100.0 10.0.26100.32230 custom x64-based Systems
CNA Microsoft Windows Server 2025 Server Core Installation affected 10.0.26100.0 10.0.26100.32230 custom x64-based Systems

References

ReferenceSourceLinkTags
msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20931 [email protected] msrc.microsoft.com Vendor Advisory
www.vicarius.io/vsociety/posts/cve-2026-20931-mitigation-script-elevation-of-... af854a3a-2127-422b-91ae-364da2661108 www.vicarius.io
www.vicarius.io/vsociety/posts/cve-2026-20931-detection-script-elevation-of-p... af854a3a-2127-422b-91ae-364da2661108 www.vicarius.io
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