CVE-2026-45659: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

High severity, CVSS 8.8. Actively exploited: in CISA KEV since 2026-07-01. EPSS: 2.7% chance of exploitation in the next 30 days.

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

Affected products

• Microsoft SharePoint Server: before 16.0.19725.20280 (fixed in 16.0.19725.20280); version 2016 only; version 2019 only

Published 2026-05-22. Last modified 2026-07-23.