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.
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describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-54338US | — | — | ||
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 unbounde… | ||||
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references
External citations — patches, advisories, analysis.
- https://github.com/advisories/GHSA-p43p-whwx-q52hADVISORY
- https://github.com/jupyterhub/jupyterhubPACKAGE
- https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0aWEB
- https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52hWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-54338ADVISORY
- https://pypi.org/project/jupyterhubPACKAGE
scry
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