CVE-2022-31027 Authorization Bypass Through User-Controlled Key when using CILogonOAuthenticator in oauthenticator

What is CVE-2022-31027?

CVE-2022-31027 is a medium-severity authentication bypass vulnerability in jupyterhub oauthenticator, published on 6 Jun 2022. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

OAuthenticator is an OAuth token library for the JupyerHub login handler. CILogonOAuthenticator is provided by the OAuthenticator package, and lets users log in to a JupyterHub via CILogon. This is primarily used to restrict a JupyterHub only to users of a given institute. The allowed_idps configuration trait of CILogonOAuthenticator is documented to be a list of domains that indicate the institutions whose users are authorized to access this JupyterHub. This authorization is validated by ensuring that the *email* field provided to us by CILogon has a *domain* that matches one of the domains listed in `allowed_idps`.If `allowed_idps` contains `berkeley.edu`, you might expect only users with valid current credentials provided by University of California, Berkeley to be able to access the JupyterHub. However, CILogonOAuthenticator does *not* verify which provider is used by the user to login, only the email address provided. So a user can login with a GitHub account that has email set to `<something>@berkeley.edu`, and that will be treated exactly the same as someone logging in using the UC Berkeley official Identity Provider. The patch fixing this issue makes a *breaking change* in how `allowed_idps` is interpreted. It's no longer a list of domains, but configuration representing the `EntityID` of the IdPs that are allowed, picked from the [list maintained by CILogon](https://cilogon.org/idplist/). Users are advised to upgrade.

Weakness: CWE-639

Which versions are affected by CVE-2022-31027?

3 open source packages ship an affected version, including oauthenticator. It affects 1 product.

Products include Jupyter Oauthenticator.

How do I fix CVE-2022-31027?

Upgrade oauthenticator to 15.0.0 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2022-31027 being exploited?

There is no known exploitation of CVE-2022-31027 in the wild and no public exploit code.

Other vulnerabilities in jupyterhub oauthenticator

• CVE-2026-33175 OAuthenticator: Authentication Bypass in Auth0OAuthenticator via Unverified Email Claims High 8.8
• CVE-2018-7206 JupyterHub OAuthenticator elevation of privilege High 8.8
• CVE-2024-29033 GoogleOAuthenticator.hosted_domain incorrectly verifies membership of an Google organization/workspace High 7.5
• CVE-2020-26250 Base class whitelist configuration ignored in OAuthenticator Medium 6.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-r7v4-jwx9-wx43, PYSEC-2022-206.