How severe is CVE-2026-33175?

CVE-2026-33175 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-33175?

CVE-2026-33175 affects the following packages: oauthenticator (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-33175?

Update oauthenticator to 17.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33175 is resolved across your whole dependency graph.

How do I detect CVE-2026-33175 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for oauthenticator, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-33175 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-33175 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33175 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33175?

CVE-2026-33175 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 39th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33175?

CVE-2026-33175 is classified as Improper Authentication (CWE-287), CWE-290 (CWE-290). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-33175 published, and has it been updated?

CVE-2026-33175 was published on April 3, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2026-33175 — oauthenticator

HIGHFix: jupyterhub/oauthenticator@f0c7002

CVE-2026-33175 is a high-severity (CVSS 8.8) Improper Authentication vulnerability in oauthenticator. A fix is available for oauthenticator — see the affected versions and patch details below.

OAuthenticator: Authentication Bypass in Auth0OAuthenticator via Unverified Email Claims

Also known asGHSA-rrvg-cxh4-qhrvPYSEC-2026-2238

Published

Apr 3, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33175.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs39th percentile — riskier than 39% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐍oauthenticator

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`oauthenticator`	all versions	17.4.0`pip install --upgrade 'oauthenticator==17.4.0'`

Affected Products

1 product · 1 configurations

Application

oauthenticatorjupyter

< 17.4.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for oauthenticator, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update oauthenticator to 17.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33175 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### 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