Microsoft Windows up to Server 2025 Telephony Service file inclusion

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
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7.3$5k-$25k0.00

Summaryinfo

A vulnerability has been found in Microsoft Windows and classified as critical. The affected element is an unknown function of the component Telephony Service. This manipulation causes file inclusion. The identification of this vulnerability is CVE-2026-20931. The attack needs to be done within the local network. There is no exploit available. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in Microsoft Windows. It has been declared as critical. Affected by this vulnerability is an unknown part of the component Telephony Service. The manipulation with an unknown input leads to a file inclusion vulnerability. The CWE definition for the vulnerability is CWE-73. The product allows user input to control or influence paths or file names that are used in filesystem operations. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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

The weakness was shared 01/13/2026 as confirmed security update guide (Website). It is possible to read the advisory at msrc.microsoft.com. This vulnerability is known as CVE-2026-20931. The exploitation appears to be easy. The attack needs to be done within the local network. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 05/27/2026).

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.3

VulDB Base Score: 8.0
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 8.0
Vendor Vector (Microsoft): 🔒

CNA Base Score: 8.0
CNA Vector (Microsoft): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: File inclusion
CWE: CWE-73
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔒
0-Day Time: 🔒
Exposure Time: 🔒

Timelineinfo

01/13/2026 VulDB entry created
01/13/2026 +0 days Advisory disclosed
01/13/2026 +0 days Countermeasure disclosed
05/27/2026 +133 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-20931 (🔒)
GCVE (CVE): GCVE-0-2026-20931
GCVE (VulDB): GCVE-100-340819
scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 01/13/2026 19:44
Updated: 05/27/2026 02:06
Changes: 01/13/2026 19:44 (30), 01/13/2026 19:45 (6), 01/13/2026 19:48 (33), 01/17/2026 06:59 (11), 05/27/2026 02:06 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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