CVE-2023-25574: JupyterHub LTI Authenticator JWT signature validation bypass

Executive brief

A security flaw in the JupyterHub LTI Authenticator allows unauthorized individuals to gain access to user accounts. This component is used to connect JupyterHub with learning management systems; because it fails to verify digital signatures, an attacker can forge login requests to impersonate existing users or create new ones. This could lead to a total compromise of the JupyterHub environment and unauthorized access to student or researcher data.

Technical details

The LTI13Authenticator class in jupyterhub-ltiauthenticator version 1.3.0 fails to perform cryptographic signature validation on JSON Web Tokens (JWT) received during the LTI 1.3 login flow. This vulnerability is located in the validator.py component. A remote, unauthenticated attacker can exploit this by sending a specially crafted, forged JWT to the authentication endpoint. Successful exploitation allows the attacker to bypass authentication entirely, granting them access to existing user identities or the ability to provision new ones. The issue is addressed in version 1.4.0.

Affected products

• JupyterHub jupyterhub-ltiauthenticator 1.3.0

Timeline

• 2023-03-01: patched: Version 1.4.0 released
• 2025-02-25: advisory: GitHub Advisory published

References

• https://api.github.com/users/consideRatio
• https://github.com/consideRatio
• https://api.github.com/users/consideRatio/gists%7B/gist_id%7D
• https://api.github.com/users/consideRatio/repos
• https://avatars.githubusercontent.com/u/3837114?v=4
• https://api.github.com/users/consideRatio/events%7B/privacy%7D