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MEDIUM severity

Base class whitelist configuration ignored in OAuthenticatorGHSA-384w-5v3f-q499

MEDIUMFix: jupyterhub/oauthenticator@a4aac19

GHSA-384w-5v3f-q499 is a medium-severity (CVSS 6.3) CWE-863 vulnerability in oauthenticator. A fix is available for oauthenticator — see the affected versions and patch details below.

Also known asCVE-2020-26250PYSEC-2020-68
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs66th percentile — riskier than 66% of all scored CVEsHighest risk
0.00%0.54%1.09%1.63%0.4%1.1%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍oauthenticator

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

What goes wrong?

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.

Who is impacted?

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.

Patches

  • Replacing deprecated c.Authenticator.whitelist = ... with c.Authenticator.allowed_users = ... avoids the issue.
  • Update oauthenticator to 0.12.2
  • Update jupyterhub helm chart to 0.10.6

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 documentation.

Workarounds

Replacing c.Authenticator.whitelist = ... with c.Authenticator.allowed_users = ... avoids the issue.

In the jupyterhub helm chart prior to 0.10.6, this can be done via hub.extraConfig:

auth:
  allowedUsers:
  - user1
  - user2

hub:
  extraConfig:
    allowedUsers: |
        # set new field not exposed in helm chart < 0.10.6
        set_config_if_not_none(c.Authenticator, "allowed_users", "auth.allowedUsers")

For more information

If you have any questions or comments about this advisory:

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIoauthenticator≥ 0.12.0&&< 0.12.20.12.2pip install --upgrade 'oauthenticator==0.12.2'

Affected Products

1 product · 1 configurations
Application
oauthenticatorjupyter
≥ 0.12.0 && < 0.12.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for oauthenticator, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update oauthenticator to 0.12.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-384w-5v3f-q499 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Impact __What goes wrong?__ 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.
O3 Security · Impact-Aware SCA

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Base class whitelist configuration ignored in OAuthenticator