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Vulnerability details: VCID-ut2a-drg6-jqeq
Vulnerability ID VCID-ut2a-drg6-jqeq
Aliases CVE-2026-33175
GHSA-rrvg-cxh4-qhrv
Summary Auth0OAuthenticator has an Authentication Bypass via Unverified Email Claims ### Summary 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. ### Impact This is an **Authentication Bypass Vulnerability**. Any Auth0 tenant leveraging the `Auth0OAuthenticator` mapping the `email` claim to the JupyterHub username is impacted. By default, Auth0 handles email verification as a user flag, not a hard block to authentication streams. If an attacker can register an account with the Auth0 tenant with an unverified email and knows the email of an existing user on the system, they can authenticate as that user. ### Patches - Upgrade oauthenticator to 17.4 ### Workarounds - Check `email_verified` field in an `Authenticator.post_auth_hook` function - Do not use `email` as the username claim - [Enforce email verification in auth0](https://support.auth0.com/center/s/article/Enforce-Email-Verification-With-Sending-Email-After-Each-Denied-Access)
Status Published
Exploitability None
Weighted Severity None
Risk None
Affected and Fixed Packages Package Details
Weaknesses (4)
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/jupyterhub/oauthenticator
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

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Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/jupyterhub/oauthenticator/commit/f0c7002dc36e41efae0f674033cf7888a21d96f9
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

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Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-07T15:48:30Z/ Found at https://github.com/jupyterhub/oauthenticator/commit/f0c7002dc36e41efae0f674033cf7888a21d96f9
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/jupyterhub/oauthenticator/releases/tag/17.4.0
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-07T15:48:30Z/ Found at https://github.com/jupyterhub/oauthenticator/releases/tag/17.4.0
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/jupyterhub/oauthenticator/security/advisories/GHSA-rrvg-cxh4-qhrv
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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none

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unchanged

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Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-07T15:48:30Z/ Found at https://github.com/jupyterhub/oauthenticator/security/advisories/GHSA-rrvg-cxh4-qhrv
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2026-33175
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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none

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unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://support.auth0.com/center/s/article/Enforce-Email-Verification-With-Sending-Email-After-Each-Denied-Access
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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unchanged

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Exploit Prediction Scoring System (EPSS)
Percentile 0.31423
EPSS Score 0.00126
Published At June 5, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-04T16:52:02.054515+00:00 GithubOSV Importer Import https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-rrvg-cxh4-qhrv/GHSA-rrvg-cxh4-qhrv.json 38.6.0