CVE-2026-54733
moodle-local_o365: Authentication bypass via unverified JWT signature in Teams SSO endpoint
- State
- Published
- Severity
- 9.3 Critical
- Published
- Jul 16, 2026
- Updated
- Jul 16, 2026
- Reserved
- Jun 15, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.3 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
- CWE-347 Improper Verification of Cryptographic Signature
Affected Products
| Product | Versions |
|---|---|
o365-moodlemicrosoft |
|
References
- https://github.com/microsoft/o365-moodle/security/advisories/GHSA-hqjh-93qv-47v5
- https://github.com/microsoft/o365-moodle/commit/01b2d4c2e13b06a66557527084cbf9bace655944
- https://github.com/microsoft/o365-moodle/commit/258872f6e2011f4efa8ebb77d2898142a9435e89
- https://github.com/microsoft/o365-moodle/commit/d5596655f0baaee0f11aec2e10d6f36b0bd29220
- https://github.com/microsoft/o365-moodle/releases/tag/v20260423_m405
- https://github.com/microsoft/o365-moodle/releases/tag/v20260423_m500
- https://github.com/microsoft/o365-moodle/releases/tag/v20260423_m501
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