CVE-2026-55040

A proof-of-concept (PoC) exploit for a critical Microsoft SharePoint vulnerability, published by cybersecurity company Rapid7 on Tuesday, is already being used in attacks. Tracked as CVE-2026-55040, this authentication bypass security flaw in the JWT token validation pipeline can be exploited by attackers without privileges to perform operations as a SharePoint site user or administrator. Microsoft patched […]