JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. (CVE-2026-54338)
Description
JupyterHub versions prior to 5.5.0 have a vulnerability where invalid input to form-based login authenticators allows unauthenticated attackers to place unbounded attacker-controlled usernames in failed-login logs. This can lead to resource exhaustion of logging and storage. The issue is fixed in version 5.5.0.
CVSS v3.1
Score 5.3medium
Affected software
pkg:deb/ubuntu/jupyterhub?arch=source&distro=jammypkg:deb/ubuntu/jupyterhub?arch=source&distro=noblepkg:deb/ubuntu/jupyterhub?arch=source&distro=stonkingpkg:deb/ubuntu/jupyterhub?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-54338 affects JupyterHub, a multi-user server for Jupyter notebooks. Before version 5.5.0, the software does not properly validate input to form-based login authenticators, enabling an unauthenticated attacker to inject arbitrarily large usernames into failed-login logs. This can cause unbounded consumption of logging and storage resources, potentially leading to denial of service conditions. The vulnerability is resolved in JupyterHub 5.5.0.
Potential Impact
The vulnerability allows unauthenticated attackers to cause resource exhaustion by injecting large attacker-controlled usernames into failed-login logs. This impacts availability by potentially consuming logging and storage resources. There is no confidentiality or integrity impact reported.
Mitigation Recommendations
Upgrade JupyterHub to version 5.5.0 or later where this issue is fixed. No other mitigation is specified or required.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-54338
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:26.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6ad3f5fb2cdf04f656663997
Added to database: 10/17/2026, 22:26:03 UTC
Last enriched: 10/18/2026, 00:49:08 UTC
Last updated: 10/18/2026, 00:49:08 UTC
Views: 2
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