CVE-2026-66305: Microsoft Skype For Business Server

High severity, CVSS 7.1. EPSS: 0.5% chance of exploitation in the next 30 days.

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

Affected products

• Microsoft Skype For Business Server: version 2015 only; version 2019 only
• Microsoft Skype For Business Server Subscription Edition: version 7.0.2046.849 only

Published 2026-09-08. Last modified 2026-09-16.