Microsoft

CVE-2026-20931: Windows Telephony Service Elevation of Privilege Vulnerability

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 24 Feb 2026. It cites 1 public report, the first from 24 Feb 2026.

recordedfuture.com

How likely is exploitation in the next 30 days?

0.8%

EPSS score, percentile 57.9 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

8.0 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

from 10.0.14393.0 to before 10.0.14393.8783
from 10.0.17763.0 to before 10.0.17763.8276
from 10.0.19044.0 to before 10.0.19044.6809
from 10.0.19045.0 to before 10.0.19045.6809
from 10.0.22631.0 to before 10.0.22631.6491
from 10.0.22631.0 to before 10.0.22631.6491

and 14 more in the table below

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

Windows Telephony Service Elevation of Privilege Vulnerability

External control of file name or path in Windows Telephony Service allows an authorized attacker to elevate privileges over an adjacent network.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

Windows Telephony Service Elevation of Privilege Vulnerability (Vendor advisory, Patch)

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Versions by product, as listed in the CVE record (20 products)

Microsoft Windows 10 Version 1607
Status	Versions
Affected	from 10.0.14393.0 to before 10.0.14393.8783

Microsoft Windows 10 Version 1809
Status	Versions
Affected	from 10.0.17763.0 to before 10.0.17763.8276

Microsoft Windows 10 Version 21H2
Status	Versions
Affected	from 10.0.19044.0 to before 10.0.19044.6809

Microsoft Windows 10 Version 22H2
Status	Versions
Affected	from 10.0.19045.0 to before 10.0.19045.6809

Microsoft Windows 11 version 23H2
Status	Versions
Affected	from 10.0.22631.0 to before 10.0.22631.6491

Microsoft Windows 11 Version 23H2
Status	Versions
Affected	from 10.0.22631.0 to before 10.0.22631.6491

Microsoft Windows 11 Version 24H2
Status	Versions
Affected	from 10.0.26100.0 to before 10.0.26100.7623

Microsoft Windows 11 Version 25H2
Status	Versions
Affected	from 10.0.26200.0 to before 10.0.26200.7623

Microsoft Windows Server 2008 R2 Service Pack 1
Status	Versions
Affected	from 6.1.7601.0 to before 6.1.7601.28117

Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation)
Status	Versions
Affected	from 6.1.7601.0 to before 6.1.7601.28117

Microsoft Windows Server 2008 Service Pack 2
Status	Versions
Affected	from 6.0.6003.0 to before 6.0.6003.23717

Microsoft Windows Server 2008 Service Pack 2 (Server Core installation)
Status	Versions
Affected	from 6.0.6003.0 to before 6.0.6003.23717

Microsoft Windows Server 2012
Status	Versions
Affected	from 6.2.9200.0 to before 6.2.9200.25868

Microsoft Windows Server 2012 (Server Core installation)
Status	Versions
Affected	from 6.2.9200.0 to before 6.2.9200.25868

Microsoft Windows Server 2012 R2
Status	Versions
Affected	from 6.3.9600.0 to before 6.3.9600.22968

Microsoft Windows Server 2012 R2 (Server Core installation)
Status	Versions
Affected	from 6.3.9600.0 to before 6.3.9600.22968

Microsoft Windows Server 2016
Status	Versions
Affected	from 10.0.14393.0 to before 10.0.14393.8783

Microsoft Windows Server 2016 (Server Core installation)
Status	Versions
Affected	from 10.0.14393.0 to before 10.0.14393.8783

Microsoft Windows Server 2019
Status	Versions
Affected	from 10.0.17763.0 to before 10.0.17763.8276

Microsoft Windows Server 2019 (Server Core installation)
Status	Versions
Affected	from 10.0.17763.0 to before 10.0.17763.8276

Source: CVE List, as of 30 Oct 2026. About the data.

Weakness

CWE-73

CWE-73: External Control of File Name or Path

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.

Timeline

Date	Event
13 Jan 2026	CVE record published
30 Jul 2026	CVE record last updated

Known exploited Microsoft vulnerabilities

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CVE-2026-65660: Microsoft SharePoint Code Injection Vulnerability (added 25 Sep 2026)
CVE-2026-81963: Microsoft Windows Link Following Vulnerability (added 8 Sep 2026)
CVE-2026-85880: Microsoft Windows Heap-Based Buffer Overflow Vulnerability (added 8 Sep 2026)
CVE-2019-1068: Microsoft SQL Server Remote Code Execution Vulnerability (added 26 Aug 2026)