{"cve":"CVE-2021-41247","nvd":{"published":"2021-11-04T18:15:08.707","modified":"2026-06-17T04:08:10.207","status":"Modified","description":"JupyterHub is an open source multi-user server for Jupyter notebooks. In affected versions users who have multiple JupyterLab tabs open in the same browser session, may see incomplete logout from the single-user server, as fresh credentials (for the single-user server only, not the Hub) reinstated after logout, if another active JupyterLab session is open while the logout takes place. Upgrade to JupyterHub 1.5. For distributed deployments, it is jupyterhub in the _user_ environment that needs patching. There are no patches necessary in the Hub environment. The only workaround is to make sure that only one JupyterLab tab is open when you log out.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","score":7.5},"cwes":["CWE-613"],"references":["https://github.com/jupyterhub/jupyterhub/commit/5ac9e7f73a6e1020ffddc40321fc53336829fe27","https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-cw7p-q79f-m2v7","https://github.com/jupyterhub/jupyterhub/commit/5ac9e7f73a6e1020ffddc40321fc53336829fe27","https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-cw7p-q79f-m2v7"],"products":["jupyter:jupyterhub"],"source":"nvd","synced_at":"2026-10-19T21:24:39.218183596+00:00"},"epss":{"cve":"CVE-2021-41247","score":0.00804,"percentile":0.56752,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-cw7p-q79f-m2v7","url":"https://osv.dev/vulnerability/GHSA-cw7p-q79f-m2v7","summary":"incomplete JupyterHub logout with simultaneous JupyterLab sessions","modified":"2026-07-08T06:28:53.199283056Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub","purl":"pkg:pypi/jupyterhub","ranges":[">=1.0.0 <1.5.0"],"fixed":["1.5.0"]}]},{"id":"PYSEC-2021-386","url":"https://osv.dev/vulnerability/PYSEC-2021-386","summary":"","modified":"2023-12-06T01:01:35.608761Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub","purl":"pkg:pypi/jupyterhub","ranges":[">=1.0.0 <1.5.0"],"fixed":["1.5.0"]}]}],"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."]}