{"id":"CVE-2021-41247","aliases":["GHSA-cw7p-q79f-m2v7","BIT-jupyterhub-2021-41247","PYSEC-2021-386"],"title":"incomplete JupyterHub logout with simultaneous JupyterLab sessions","summary":"incomplete JupyterHub logout with simultaneous JupyterLab sessions","severity":"low","cvss":3.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N","vendor":"jupyterhub","product":"jupyterhub","ecosystem":"pip","affected":["jupyterhub >= 1.0.0, < 1.5.0"],"patched":["jupyterhub 1.5.0"],"published":"2021-11-08","updated":"2026-07-08","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-cw7p-q79f-m2v7","references":[{"url":"https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-cw7p-q79f-m2v7"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41247"},{"url":"https://github.com/jupyterhub/jupyterhub/commit/5ac9e7f73a6e1020ffddc40321fc53336829fe27"},{"url":"https://github.com/jupyterhub/jupyterhub"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/jupyterhub/PYSEC-2021-386.yaml"}],"tags":["osv","pip"],"epss":0.00804,"epssPercentile":0.54762,"ingestedAt":"2026-07-08T18:25:48.593Z","slug":"CVE-2021-41247","body":"## Overview\n\n### Impact\n\nUsers of JupyterLab with JupyterHub 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.\n\n### Patches\n\nUpgrade 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.\n\n### Workarounds\n\nThe only workaround is to make sure that only one JupyterLab tab is open when you log out.\n\n## Affected packages\n\n- `jupyterhub >= 1.0.0, < 1.5.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `jupyterhub 1.5.0`","depth":"sunlit","depthScore":19,"depthScoreParts":{"impact":19.3,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}