CVE-2026-54338

Name	CVE-2026-54338
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
jupyterhub (PTS)	bookworm	3.0.0+ds1-1	vulnerable
	trixie	5.2.1+ds1-4	vulnerable
	forky, sid	5.2.1+ds1-5	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
jupyterhub	source	(unstable)	(unfixed)

Notes

https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h
Fixed by: https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a (5.5.0)