{"id":"CVE-2021-41194","details":"FirstUseAuthenticator is a JupyterHub authenticator that helps new users set their password on their first login to JupyterHub. When JupyterHub is used with FirstUseAuthenticator, a vulnerability in versions prior to 1.0.0 allows unauthorized access to any user's account if `create_users=True` and the username is known or guessed. One may upgrade to version 1.0.0 or apply a patch manually to mitigate the vulnerability. For those who cannot upgrade, there is no complete workaround, but a partial mitigation exists. One can disable user creation with `c.FirstUseAuthenticator.create_users = False`, which will only allow login with fully normalized usernames for already existing users prior to jupyterhub-firstuserauthenticator 1.0.0. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until a patch or upgrade occurs.","aliases":["GHSA-5xvc-vgmp-jgc3","PYSEC-2021-384"],"modified":"2026-07-09T12:20:38.636750Z","published":"2021-10-28T20:15:07.680Z","references":[{"type":"ADVISORY","url":"https://github.com/jupyterhub/firstuseauthenticator/security/advisories/GHSA-5xvc-vgmp-jgc3"},{"type":"FIX","url":"https://github.com/jupyterhub/firstuseauthenticator/pull/38"},{"type":"FIX","url":"https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/jupyterhub/firstuseauthenticator","events":[{"introduced":"0"},{"fixed":"9585ceaaf4ffb466adfe05af836124dc0ac470e7"}],"database_specific":{"cpe":"cpe:2.3:a:jupyterhub:first_use_authenticator:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.0.0"}],"source":"CPE_RANGE"}}],"versions":["v0.14.1","v0.14.0","0.13.0","v0.12","v0.11.1","v0.11"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-41194.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}