CVE-2026-54733
CriticalCVSS 9.3Summary
The Microsoft 365 and Microsoft Entra ID Plugins for Moodle have a vulnerability in the Teams SSO endpoint (sso_login.php) that base64-decodes a JWT payload and authenticates users from the upn claim without verifying the JWT signature. An unauthenticated attacker can forge a token and obtain a Moodle session as an O365-authenticated user.
Risk Assessment
The organization is at risk of unauthorized access to Moodle, allowing an attacker to impersonate any O365 user, leading to data confidentiality and integrity breaches.
Recommendation
Immediately update the Microsoft Office 365 Integration plugin (local_o365) to version 4.5.6, 5.0.5, or 5.1.1, depending on your Moodle version.
Original NVD description (English source)
The Microsoft 365 and Microsoft Entra ID Plugins for Moodle provide Office 365 and Azure Active Directory integration for Moodle. Prior to 4.5.6, 5.0.5, and 5.1.1, the Microsoft Office 365 Integration plugin local_o365 Teams SSO endpoint sso_login.php base64-decodes a JWT payload and authenticates users from the upn claim without verifying the JWT signature, allowing an unauthenticated attacker to forge a token and obtain a Moodle session as an O365-authenticated user. This issue is fixed in versions 4.5.6, 5.0.5, and 5.1.1.