EUVD-2026-17207
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
OpenOlat is an open source web-based e-learning platform for teaching, learning, assessment and communication. From version 10.5.4 to before version 20.2.5, OpenOLAT's OpenID Connect implicit flow implementation does not verify JWT signatures. The JSONWebToken.parse() method silently discards the signature segment of the compact JWT (header.payload.signature), and the getAccessToken() methods in both OpenIdConnectApi and OpenIdConnectFullConfigurableApi only validate claim-level fields (issuer, audience, state, nonce) without any cryptographic signature verification against the Identity Provider's JWKS endpoint. This issue has been patched in version 20.2.5.
Analysis
Authentication bypass in OpenOlat e-learning platform versions 10.5.4 through 20.2.4 allows remote unauthenticated attackers to forge authentication tokens due to missing JWT signature verification in OpenID Connect implementation. The platform accepts JWTs without cryptographic validation, enabling attackers to impersonate any user by crafting tokens with arbitrary claims. …
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Remediation
Within 24 hours: Inventory all OpenOlat deployments and confirm installed versions against affected range (10.5.4-20.2.4); isolate or disable external OpenID Connect integrations if possible. Within 7 days: Contact OpenOlat vendor for emergency patch timeline and escalate to institutional leadership on risk tolerance pending remediation. …
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External POC / Exploit Code
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