Review reviewHigh

CVE-2026-33175

jupyterhub oauthenticator

OAuthenticator is software that allows OAuth2 identity providers to be plugged in and used with JupyterHub. Prior to version 17.4.0, an authentication bypass vulnerability in oauthenticator allows an attacker with an unverified email address on an Auth0 tenant to login to JupyterHub. When email is used as the usrname_claim, this gives users control over their username and the possibility of account takeover. This issue has been patched in version 17.4.0.

CVSS: 8.8
EPSS: 0.44%
CISA KEV: Not listed
Published: 2026.04.04

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.44%

Technical severityCVSS 8.8

Vulnerability overview

Affected product and versions

Product: jupyterhub oauthenticator
Affected versions: >= < 17.4.0, < 17.4.0
Fixed versions: 17.4.0

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that jupyterhub oauthenticator and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-287, CWE-290