Vulnerability Analysis CVE-2026-55040 Microsoft SharePoint JWT Token Authentication Bypass
Introduction In recent enterprise security developments, a severe authentication bypass vulnerability designated as CVE-2026-55040 was disclosed in Microsoft SharePoint Server. Rated with a CVSS v3.1 base score of 9.1 (Critical), this flaw exposes on-premises SharePoint deployments to unauthenticated remote exploitation. Originally discovered by security researcher Stephen Fewer at Rapid7 Labs, the vulnerability lies deep within SharePoint’s identity handling and JSON Web