CVE-2021-26421: Microsoft Lync Server

Medium severity, CVSS 6.5. EPSS: 1.4% chance of exploitation in the next 30 days.

Skype for Business and Lync Spoofing Vulnerability

Affected products

• Microsoft Lync Server: version 2013 only
• Microsoft Skype For Business Server: version 2015 only

Published 2021-05-11. Last modified 2026-06-17.