CVE-2020-26250 Information

Description

OAuthenticator is an OAuth login mechanism for JupyterHub. In oauthenticator from version 0.12.0 and before 0.12.2 the deprecated (in jupyterhub 1.2) configuration Authenticator.whitelist which should be transparently mapped to Authenticator.allowed_users with a warning is instead ignored by OAuthenticator classes resulting in the same behavior as if this configuration has not been set. If this is the only mechanism of authorization restriction (i.e. no group or team restrictions in configuration) then all authenticated users will be allowed. Provider-based restrictions including deprecated values such as GitHubOAuthenticator.org_whitelist are not affected. All users of OAuthenticator 0.12.0 and 0.12.1 with JupyterHub 1.2 (JupyterHub Helm chart 0.10.0-0.10.5) who use the admin.whitelist.users configuration in the jupyterhub helm chart or the c.Authenticator.whitelist configuration directly. Users of other deprecated configuration e.g. c.GitHubOAuthenticator.team_whitelist are not affected. If you see a log line like this and expect a specific list of allowed usernames: [I 2020-11-27 16:51:54.528 JupyterHub app:1717] Not using allowed_users. Any authenticated user will be allowed.\ you are likely affected. Updating oauthenticator to 0.12.2 is recommended. A workaround is to replace the deprecated c.Authenticator.whitelist = ... with c.Authenticator.allowed_users = .... If any users have been authorized during this time who should not have been they must be deleted via the API or admin interface per the referenced documentation.

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Reference

https://github.com/jupyterhub/oauthenticator/blob/master/docs/source/changelog.md#0122—2020-11-30 https://github.com/jupyterhub/oauthenticator/commit/a4aac191c16cf6281f3d346615aefa75702b02d7 https://jupyterhub.readthedocs.io/en/1.2.2/getting-started/authenticators-users-basics.html#add-or-remove-users-from-the-hub https://github.com/jupyterhub/oauthenticator/security/advisories/GHSA-384w-5v3f-q499

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

HIGH

Availability Impact

NONE

Base Score

NONE

Base Severity

6.3