CVE-2026-55040

Name of the Vulnerable Software and Affected Versions Microsoft Office SharePoint (affected versions not specified)

Description Weak authentication in Microsoft Office SharePoint allows an unauthenticated remote attacker to bypass security features over a network. The issue resides in the JWT token validation pipeline, where JSON Web Tokens (JWT)—a compact, URL-safe means of representing claims to be transferred between two parties—are not properly validated. Successful exploitation enables an attacker to perform operations as a SharePoint site user or administrator, potentially leading to remote code execution and privilege escalation on the server. Approximately 14,000 potentially exposed systems have been identified via internet-exposure search data.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.