CVE-2026-20963: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Critical severity, CVSS 9.8. Actively exploited: in CISA KEV since 2026-03-18. EPSS: 29.2% chance of exploitation in the next 30 days.

Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

Affected products

• Microsoft SharePoint Server: before 16.0.19127.20442 (fixed in 16.0.19127.20442); version 2016 only; version 2019 only

Published 2026-01-13. Last modified 2026-06-17.