computerworld.com • 20h
Critical Hardening Required for Microsoft SharePoint On-Premises Deployments
CISA has added several Microsoft SharePoint on-premises vulnerabilities to the Known Exploited Vulnerabilities (KEV) catalog, signaling active weaponization. The attack surface includes critical RCE via insecure deserialization (CVE-2026-58644, CVSS 9.8) and unauthenticated remote exploitation via CVE-2026-56164. These flaws enable attackers to establish initial footholds, facilitating lateral movement toward Domain Controllers and backup systems for full infrastructure encryption. Remediation requires immediate patching, AMSI integration, and the rotation of SharePoint machine keys to neutralize persistent access.