The U.S. Cybersecurity and Infrastructure Security Agency has added a critical Microsoft SharePoint Server vulnerability to its Known Exploited Vulnerabilities catalog, mandating federal agency patches by July 19, 2026.

Key Points

• The vulnerability, CVE-2026-58644, carries a critical CVSS score of 9.8 and allows unauthorized remote code execution.
• Affected software includes Microsoft SharePoint Server Subscription Edition, 2019, and 2016.
• Microsoft confirmed the flaw was exploited as a zero-day before patches were released on July 14, 2026.
• CISA also added two critical Fortinet FortiSandbox vulnerabilities, CVE-2026-25089 and CVE-2026-39808, to the mandatory remediation list.
• Recommended hardening measures include enabling Antimalware Scan Interface integration and restricting direct internet exposure for SharePoint servers.

Why it Matters

This directive highlights the ongoing risk of remote code execution attacks targeting widely used enterprise infrastructure. By mandating rapid remediation, CISA aims to prevent threat actors from gaining persistent access to sensitive government networks through weaponized software flaws.