Auth bypass in Jupyter Oauthenticator
CVE-2026-33175
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.
Vulnerability class: Broken Authentication
EPSS: 0.004 (35.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Jupyter Oauthenticator
- Jupyterhub Oauthenticator — versions < 17.4.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Product, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-33175?
- CVE-2026-33175 is a high-severity vulnerability in Jupyter Oauthenticator, classified under Improper Authentication. CVSS score: 8.8/10. Published 2026-04-03.
- How severe is CVE-2026-33175?
- High severity. CVSS v3 base score is 8.8 out of 10.