Input validation error in jupyterhub - #VU162718
Published: November 9, 2026
Vulnerability identifier: #VU162718
CSH Severity: Medium
CVSS v4: 8.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/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 a low-privileged attacker to gain administrator access to JupyterHub through a process requiring interaction by an administrator.
The vulnerability exists due to missing username normalization in SharedPasswordAuthenticator when the authenticator is configured with admin_users. A low-privileged attacker can exploit this normalization failure, with administrator interaction, to elevate their own account privileges.
Affected software
jupyterhub
Remediation
Install security update from vendor's website.
jupyterhub - addressed in versions 5.5.3, 6.1.0