Input validation error in jupyterhub - #VU162719
Published: November 9, 2026
Vulnerability identifier: #VU162719
CSH Severity: Low
CVSS v4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an administrator with permission to rename users to create invalid usernames that may lead to cross-site scripting.
The vulnerability exists due to missing username validation in JupyterHub's administrative API when an existing user is renamed. An administrator with permission to rename users can submit a crafted username that could execute script in another user's browser when that user views affected content.
Affected software
jupyterhub
Remediation
Install security update from vendor's website.
jupyterhub - addressed in versions 5.5.3, 6.1.0