Resource exhaustion in Jupyterhub
CVE-2026-54338
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, allowi…
Vulnerability class: DoS (Denial of Service)
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
Affected products
- Jupyterhub — versions < 5.5.0JupyterHub 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.
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-54338?
- CVE-2026-54338 is a medium-severity vulnerability in Jupyterhub, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-08-07.
- How severe is CVE-2026-54338?
- Medium severity. CVSS v3 base score is 5.3 out of 10.