CVE-2026-54338

JupyterHub: Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login

Published Aug 7, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-p43p-whwx-q52h JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Jupyterhub
Jupyterhub jupyterhub
Vendors & Products Jupyterhub
Jupyterhub jupyterhub
Type Values Removed Values Added
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.
Title JupyterHub: Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login
Weaknesses CWE-400
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 11, 2026, 1:15 AM
Reserved
Jun 12, 2026, 7:23 PM
Status
Awaiting Analysis
Published
Aug 7, 2026, 9:17 PM
Modified
Sep 9, 2026, 8:58 PM