Active Exploitation of Microsoft SharePoint Flaw CVE-2026-45659 Confirmed

CVE-2026-45659 is a critical remote code execution vulnerability in Microsoft SharePoint (affecting SharePoint Server Subscription Edition, 2019, and Enterprise Server 2016) caused by untrusted data deserialization; CISA has added it to its Known Exploited Vulnerabilities catalog and mandated federal patching by July 4, 2026. Microsoft released a patch on May 21, 2026, but bulletin details were omitted; organizations are urged to verify patch levels and enact incident response if not updated.