{"cve":"CVE-2021-41194","nvd":{"published":"2021-10-28T20:15:07.680","modified":"2026-06-17T04:08:04.187","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-284"],"references":["https://github.com/jupyterhub/firstuseauthenticator/pull/38","https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch","https://github.com/jupyterhub/firstuseauthenticator/security/advisories/GHSA-5xvc-vgmp-jgc3","https://github.com/jupyterhub/firstuseauthenticator/pull/38","https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch"],"products":["jupyterhub:first_use_authenticator"],"source":"nvd","synced_at":"2026-10-19T21:24:39.218183596+00:00"},"epss":{"cve":"CVE-2021-41194","score":0.01367,"percentile":0.71861,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-5xvc-vgmp-jgc3","url":"https://osv.dev/vulnerability/GHSA-5xvc-vgmp-jgc3","summary":"Improper Access Control in jupyterhub-firstuseauthenticator","modified":"2026-07-08T06:28:40.246890047Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub-firstuseauthenticator","purl":"pkg:pypi/jupyterhub-firstuseauthenticator","ranges":["<1.0.0"],"fixed":["1.0.0"]}]},{"id":"PYSEC-2021-384","url":"https://osv.dev/vulnerability/PYSEC-2021-384","summary":"","modified":"2023-11-08T04:06:54.528947Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub-firstuseauthenticator","purl":"pkg:pypi/jupyterhub-firstuseauthenticator","ranges":["<1.0.0"],"fixed":["1.0.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}