{"id":"PYSEC-2026-1480","summary":"Cross site scripting (XSS) in JupyterHub via Self-XSS leveraged by Cookie Tossing","details":"### Impact\n\nAffected configurations:\n\n- Single-origin JupyterHub deployments\n- JupyterHub deployments with user-controlled applications running on subdomains or peer subdomains of either the Hub or a single-user server.\n\nBy tricking a user into visiting a malicious subdomain, the attacker can achieve an XSS directly affecting the former's session. More precisely, in the context of JupyterHub, this XSS could achieve the following:\n\n- Full access to JupyterHub API and user's single-user server, e.g.\n  - Create and exfiltrate an API Token\n  - Exfiltrate all files hosted on the user's single-user server: notebooks, images, etc.\n  - Install malicious extensions. They can be used as a backdoor to silently regain access to victim's session anytime.\n\n### Patches\n\nTo prevent cookie-tossing:\n\n- Upgrade to JupyterHub 4.1 (both hub and user environment)\n- enable per-user domains via `c.JupyterHub.subdomain_host = \"https://mydomain.example.org\"`\n- set `c.JupyterHub.cookie_host_prefix_enabled = True` to enable domain-locked cookies\n\nor, if available (applies to earlier JupyterHub versions):\n\n- deploy jupyterhub on its own domain, not shared with any other services\n- enable per-user domains via `c.JupyterHub.subdomain_host = \"https://mydomain.example.org\"`","aliases":["BIT-jupyterhub-2024-28233","CVE-2024-28233","GHSA-7r3h-4ph8-w38g"],"modified":"2026-07-07T17:56:55.794570733Z","published":"2026-07-07T11:45:36.867733Z","references":[{"type":"WEB","url":"https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-7r3h-4ph8-w38g"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-28233"},{"type":"FIX","url":"https://github.com/jupyterhub/jupyterhub/commit/e2798a088f5ad45340fe79cdf1386198e664f77f"},{"type":"PACKAGE","url":"https://github.com/jupyterhub/jupyterhub"},{"type":"PACKAGE","url":"https://pypi.org/project/jupyterhub"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-7r3h-4ph8-w38g"}],"affected":[{"package":{"name":"jupyterhub","ecosystem":"PyPI","purl":"pkg:pypi/jupyterhub"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.1.0"}]}],"versions":["0.1.0","0.2.0","0.3.0","0.4.0","0.4.1","0.5.0","0.6.0","0.6.1","0.7.0","0.7.0b1","0.7.1","0.7.2","0.8.0","0.8.0b1","0.8.0b2","0.8.0b3","0.8.0b4","0.8.0b5","0.8.0rc1","0.8.0rc2","0.8.1","0.9.0","0.9.0b1","0.9.0b2","0.9.0b3","0.9.0rc1","0.9.1","0.9.2","0.9.3","0.9.4","0.9.5","0.9.6","1.0.0","1.0.0b1","1.0.0b2","1.1.0","1.1.0b1","1.2.0","1.2.0b1","1.2.1","1.2.2","1.3.0","1.4.0","1.4.1","1.4.2","1.5.0","1.5.1","2.0.0","2.0.0b1","2.0.0b2","2.0.0b3","2.0.0rc1","2.0.0rc2","2.0.0rc3","2.0.0rc4","2.0.0rc5","2.0.1","2.0.2","2.1.0","2.1.1","2.2.0","2.2.1","2.2.2","2.3.0","2.3.1","3.0.0","3.0.0b1","3.1.0","3.1.1","4.0.0","4.0.0b1","4.0.0b2","4.0.1","4.0.2"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/jupyterhub/PYSEC-2026-1480.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N"}]}