moodle-local_o365: Authentication bypass via unverified JWT signature in Teams SSO endpoint
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-347.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Microsoft | o365-moodle | before 4.5.6; 5.0.0 to before 5.0.5; 5.1.0 to before 5.1.1 | 4.5.6, 5.0.5, 5.1.1 | Patch available | CNA |
- o365-moodle VendorMicrosoft Affected before 4.5.6; 5.0.0 to before 5.0.5; 5.1.0 to before 5.1.1 Fixed in 4.5.6, 5.0.5, 5.1.1 Patch available CNA
Remediation
- Fix · CNA o365-moodle (microsoft) Fixed in 4.5.6, 5.0.5, 5.1.1
Timeline
- 2026-10-02 Threatist record created from CVE-2026-54733
References
Other 7
- 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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Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences