JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login
Impact
Invalid input to login resulted in unbounded logging output. Only form-based Authenticators (the default PAM Authenticator, but not the more widely used OAuthenticator) are affected.
Patches
Upgrade to 5.5.0.
Workarounds
Use an Authenticator that doesn't use a login form, such as OAuthenticator.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | jupyterhub | < 5.5.0 | 5.5.0 |
References
- https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h
- https://nvd.nist.gov/vuln/detail/CVE-2026-54338
- https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a
- https://github.com/jupyterhub/jupyterhub
- https://pypi.org/project/jupyterhub
- https://github.com/advisories/GHSA-p43p-whwx-q52h
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-400- Platform
- Python (PyPI)
- Package
jupyterhub- Disclosed
- 25.08.2026
- Updated
- 11.10.2026 15:18
Sources and licenses
OSV / GitHub Advisory Database - GHSA-p43p-whwx-q52h - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-3853 - PyPA Advisory Database; CC BY 4.0
Vulnerability history: jupyterhub
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 8
- First → latest
- 04.2019 08.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 6
Disclosures per year
- 2019: 1
- 2020: 0
- 2021: 2
- 2022: 0
- 2023: 0
- 2024: 2
- 2025: 0
- 2026: 3
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JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login this entry
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