OAuthenticator: Authentication Bypass in Auth0OAuthenticator via Unverified Email Claims

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Summary

CVECVE-2026-33175
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-03 22:16:26 UTC
Updated2026-04-03 22:16:26 UTC
DescriptionOAuthenticator 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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-287 | CWE-290 | CWE-287 CWE-287: Improper Authentication | CWE-290 CWE-290: Authentication Bypass by Spoofing

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jupyterhub Oauthenticator affected < 17.4.0 Not specified

References

ReferenceSourceLinkTags
github.com/jupyterhub/oauthenticator/commit/f0c7002dc36e41efae0f674033cf... [email protected] github.com
github.com/jupyterhub/oauthenticator/security/advisories/GHSA-rrvg-cxh4-... [email protected] github.com
github.com/jupyterhub/oauthenticator/releases/tag/17.4.0 [email protected] github.com
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