Description
JupyterHub through 6.0.1 contains an identifier collision vulnerability that allows authenticated users to overwrite another user's named-server OAuth client by registering a hyphenated username. Attackers holding a name like alice-prod can overwrite the client for alice's server prod, breaking OAuth login and revoking tokens by stopping their own server.
References6
- github.com/jupyterhub/jupyterhub
- github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455b…
- github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455b…
- github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455b…
- hackmd.io/@haind/jupyterhub-oauth-client-id-cross-user-collision
- www.vulncheck.com/advisories/jupyterhub-through-6.0.1-oauth-cli…
Metrics
- CVSS 3.1
-
4.2
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L - CVSS 4.0
-
2.3
LOW
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 16 · as of 11 November 2026
- CWE
- CWE-694
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.