Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Microsoft Skype for Business Server 2015 CU13 affected
Version Status Constraints
9319.0 affected < 6.0.9319.885
Microsoft Skype for Business Server 2019 CU8 affected
Version Status Constraints
2046.0 affected < 7.0.2046.569
Microsoft Skype for Business Server Subscription Edition CU1 affected
Version Status Constraints
2046.0 affected < 7.0.2046.879

No data.

No data.

No data.

Project Subscriptions

Vendors Products
Microsoft Subscribe
Skype For Business Server 2015 Subscribe
Skype For Business Server 2019 Subscribe
Skype For Business Server Subscription Edition Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66305 cve-icon
History

Tue, 08 Sep 2026 18:45:00 +0000

Type Values Removed Values Added
Description Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
Title Skype for Business Spoofing Vulnerability
First Time appeared Microsoft
Microsoft skype For Business Server 2015
Microsoft skype For Business Server 2019
Microsoft skype For Business Server Subscription Edition
Weaknesses CWE-603
CPEs cpe:2.3:a:microsoft:skype_for_business_server_2015:*:cu13:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server_2019:*:cu8:*:*:*:*:*:*
cpe:2.3:a:microsoft:skype_for_business_server_subscription_edition:*:cu1:*:*:*:*:*:*
Vendors & Products Microsoft
Microsoft skype For Business Server 2015
Microsoft skype For Business Server 2019
Microsoft skype For Business Server Subscription Edition
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N/E:U/RL:O/RC:C'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: microsoft

Published:

Updated: 2026-09-08T18:32:29.324Z

Reserved: 2026-07-24T18:06:51.294Z

Link: CVE-2026-66305

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses