CVE-2020-26250

Base class whitelist configuration ignored in OAuthenticator

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.

Category

6.3
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.41%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory readthedocs.io
Affected: jupyterhub oauthenticator
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2020-26250?
CVE-2020-26250 has been scored as a medium severity vulnerability.
How to fix CVE-2020-26250?
To fix CVE-2020-26250, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2020-26250 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2020-26250 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2020-26250?
CVE-2020-26250 affects jupyterhub oauthenticator.
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