ToolShell Threat Brief: SharePoint RCE Vulnerabilities (CVE-2025-53770 & 53771) Explained
A serious new vulnerability (CVE-2025-53770, also known as “ToolShell”) is actively being exploited by cybercriminals to hack into on-premises Microsoft SharePoint Servers. The vulnerability, along with CVE-2025-53771 was discovered around July 18, 2025. Bitsight Research classifies CVE-2025-53770 as 10 out of 10 on our Dynamic Vulnerability Exploit (DVE) scale and CVE-2025-53771 as a 5.82 out of 10 indicating severe and moderate urgency respectively.