{"id":"GHSA-5xvc-vgmp-jgc3","summary":"Improper Access Control in jupyterhub-firstuseauthenticator","details":"### Impact\n\nWhen JupyterHub is used with FirstUseAuthenticator, the vulnerability allows unauthorized access to any user's account if `create_users=True` and the username is known or guessed.\n\n### Patches\n\nUpgrade to jupyterhub-firstuseauthenticator to 1.0, or apply patch https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch\n\n### Workarounds\n\nIf you cannot upgrade, there is no complete workaround, but it can be mitigated.\n\nIf you cannot upgrade yet, you 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. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until you can patch or upgrade.","aliases":["CVE-2021-41194","PYSEC-2021-384"],"modified":"2026-07-08T06:28:40.246890047Z","published":"2021-10-28T23:13:57Z","database_specific":{"cwe_ids":["CWE-284"],"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2021-10-28T16:52:16Z","nvd_published_at":"2021-10-28T20:15:00Z"},"references":[{"type":"WEB","url":"https://github.com/jupyterhub/firstuseauthenticator/security/advisories/GHSA-5xvc-vgmp-jgc3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41194"},{"type":"WEB","url":"https://github.com/jupyterhub/firstuseauthenticator/pull/38"},{"type":"WEB","url":"https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch"},{"type":"WEB","url":"https://github.com/jupyterhub/firstuseauthenticator/pull/38/commits/32b21898fb2b53b1a2e36270de6854ad70e9e9bf"},{"type":"WEB","url":"https://github.com/jupyterhub/firstuseauthenticator/pull/38/commits/9e200d974e0cb85d828a6afedb8ab90a37878f28"},{"type":"WEB","url":"https://github.com/jupyterhub/firstuseauthenticator/commit/953418e2450dbc2d854e332350849533b0ebc7ba"},{"type":"PACKAGE","url":"https://github.com/jupyterhub/firstuseauthenticator"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/jupyterhub-firstuseauthenticator/PYSEC-2021-384.yaml"}],"affected":[{"package":{"name":"jupyterhub-firstuseauthenticator","ecosystem":"PyPI","purl":"pkg:pypi/jupyterhub-firstuseauthenticator"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.0.0"}]}],"versions":["0.10","0.11","0.12","0.13.0","0.14.0","0.14.1","0.9"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/10/GHSA-5xvc-vgmp-jgc3/GHSA-5xvc-vgmp-jgc3.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"}]}