Vulnerability · Published Oct 11, 2026 · Assigned by VulnCheck
CVE-2026-108752JupyterHub through 6.0.1 OAuth Client ID Collision via Unescaped Hyphen
Medium 4.2
In plain English
A medium-severity security flaw in jupyterhub from jupyterhub. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities).
Severity (CVSS 3.1)4.2Medium
Exploit odds (30 days)0.2%top 84.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | jupyterhub | no fix listed | DEBIAN-CVE-2026-108752 |
| Debian:13 | jupyterhub | no fix listed | DEBIAN-CVE-2026-108752 |
| Debian:14 | jupyterhub | no fix listed | DEBIAN-CVE-2026-108752 |
| Ubuntu:22.04:LTS | jupyterhub | no fix listed | UBUNTU-CVE-2026-108752 |
| Ubuntu:24.04:LTS | jupyterhub | no fix listed | UBUNTU-CVE-2026-108752 |
| Ubuntu:26.04:LTS | jupyterhub | no fix listed | UBUNTU-CVE-2026-108752 |
| Ubuntu:26.10 | jupyterhub | no fix listed | UBUNTU-CVE-2026-108752 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| jupyterhub | jupyterhub | 0 – through 6.0.1 |
Weakness: CWE-694 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L
References
- https://hackmd.io/@haind/jupyterhub-oauth-client-id-cross-user-collision third-party-advisory
- https://github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455befb2f14d80d337b/jupyterhub/user.py#L563-L567 technical-description
- https://github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455befb2f14d80d337b/jupyterhub/oauth/provider.py#L719-L754 technical-description
- https://github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455befb2f14d80d337b/jupyterhub/user.py#L1174-L1186 technical-description
- https://github.com/jupyterhub/jupyterhub product
- VulnCheck Advisory: JupyterHub through 6.0.1 OAuth Client ID Collision via Unescaped Hyphen third-party-advisory