Act
archived
CISA KEV: SharePoint RCE Zero-Day CVE-2026-58644 Actively Exploited
- Engineer — Act: SharePoint Server CVE-2026-58644 (CVSS 9.8) is KEV-listed with active exploitation and a public GitHub PoC — patch immediately; federal deadline is July 19, 2026, so treat this as emergency priority regardless of your organization type.
- SOC/IR — Act: With active exploitation confirmed and a public PoC live, treat any on-prem SharePoint Server as potentially compromised — sweep SharePoint ULS/IIS logs for deserialization anomalies and unusual POST requests to SharePoint endpoints since the vulnerability was disclosed.
- Leader — Act: A CVSS 9.8 SharePoint RCE is actively exploited and KEV-listed with a two-day federal remediation deadline — confirm this week whether your environment runs SharePoint Server on-prem and verify the engineering team has emergency patching underway before the July 19 deadline.
- Signals: CVE-2026-58644 — CISA KEV: listed, EPSS 0.01, public PoC on GitHub
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