What’s Vulnerable › Vulnerabilities

CVE-2026-54733: moodle-local_o365: Authentication bypass via unverified JWT signature in Teams SSO endpoint

• Severity: critical (CVSS 9.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-16 · updated 2026-10-24
• Weakness: CWE-347

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.

Affected products

• microsoft o365-moodle: before 4.5.6; from 5.0.0, < 5.0.5; from 5.1.0, < 5.1.1

References

• 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
• https://github.com/microsoft/o365-moodle/security/advisories/GHSA-hqjh-93qv-47v5

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