CVE-2026-54338
Medium
Description
JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources. This issue is fixed in version 5.5.0.
SeverityMedium
CVSS5.3
Exploit probability—
ProductJupyterhub
PublishedAug 7, 2026
First seenAug 7, 2026
Weakness typeCWE-400Uncontrolled resource consumption
How to fix
Update
- jupyterhub5.5.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| jupyterhubPyPI | v < 5.5.0 | 5.5.0 |
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