OAuth client ID collision in JupyterHub via hyphenated usernames
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · Low
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
JupyterHub through 6.0.1 contains an identifier collision flaw (CWE-694) that lets an authenticated user overwrite another user's named-server OAuth client by registering a hyphenated username. An attacker who holds a name like alice-prod can replace the client for alice's prod server, which breaks OAuth login and revokes tokens when the attacker stops their own server. The CVSS 4.0 base score is 2.3 (LOW).
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| jupyterhub | jupyterhub | up to 6.0.1 | — | No fix listed | CNA |
- jupyterhub Vendorjupyterhub Affected up to 6.0.1 Fixed in — No fix listed CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:jupyter:jupyterhub:*:*:*:*:*:*:*:* | — | — | jupyterlab |
- cpe:2.3:a:jupyter:jupyterhub:*:*:*:*:*:*:*:* Versions — — ·jupyterlab
Remediation
The sources list no fixed version for jupyterhub.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Timeline
- 2026-10-11 Threatist record created from CVE-2026-108752
- 2026-10-11 Alias added: GHSA-h63v-vvgj-vrfh
- 2026-10-13 CISA SSVC decision points changed
References
Other 4
- https://github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455befb2f14d80d337b/jupyterhub/user.py#L563-L567
- https://github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455befb2f14d80d337b/jupyterhub/oauth/provider.py#L719-L754
- https://github.com/jupyterhub/jupyterhub/blob/3e516c6f382b481e815ec455befb2f14d80d337b/jupyterhub/user.py#L1174-L1186
- https://github.com/jupyterhub/jupyterhub
More jupyterhub vulnerabilities
- TI-2025-23499 Jupyter Remote Desktop Proxy makes TigerVNC accessible via the network and not just via a UNIX socket as intended CVSS 4.0CRITICAL 9.0
- TI-2023-10877 JupyterHub's LTI13Authenticator: JWT signature not validated CVSS 3.1CRITICAL 10.0
- TI-2021-16545 Remote code execution in Binderhub CVSS 3.1CRITICAL 9.8
- TI-2021-18033 Improper Access Control in jupyterhub-firstuseauthenticator CVSS 3.1CRITICAL 9.8
- TI-2021-16546 Code injection in nbgitpuller CVSS 3.1CRITICAL 9.6
- TI-2024-18755 Jupyter Server Proxy's Websocket Proxying does not require authentication CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-108752 · CVE Program
- CVE-2026-108752 · NVD
- FIRST EPSS
- GHSA-h63v-vvgj-vrfh · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences