ToolShell in the Wild: Microsoft SharePoint Zero-Day (CVE-2025-53770 & CVE-2025-53771)

What You Need To Know
Microsoft's zero-day vulnerability chain–codenamed ToolShell–combines CVE-2025-53770 (deserialization) and CVE-2025-53771 (authentication bypass) to enable unauthenticated remote code execution (RCE) on on-premises SharePoint Server. This exploit actively used by threat actors and has caused widespread compromise.