Act
active
SharePoint Auth Bypass CVE-2026-55040 Actively Exploited After PoC
- Engineer — Act: SharePoint CVSS 9.1 authentication bypass is now under active exploitation following public PoC release; apply Microsoft’s July 2026 Patch Tuesday update to all on-premises and hybrid SharePoint instances immediately and verify patch status in your estate.
- SOC/IR — Act: Active exploitation of a SharePoint auth bypass means adversaries may already be inside unpatched tenants; hunt for anomalous SharePoint authentication events and unexpected file access patterns in audit logs dating back to the PoC release.
- Leader — Act: SharePoint is ubiquitous in enterprise environments and this critical auth bypass is under active attack; confirm patch completion with engineering this week and assess whether any exposure window existed that could trigger customer notification obligations.
- Signals: CVE-2026-55040 — CISA KEV: not listed, EPSS 0.02, public PoC on GitHub
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