GHSA-r7v4-jwx9-wx43 is a medium-severity (CVSS 4.2) CWE-639 vulnerability in oauthenticator. A fix is available for oauthenticator — see the affected versions and patch details below.
Authorization Bypass Through User-Controlled Key when using CILogonOAuthenticator oauthenticator
Exploitation Status
No confirmed exploitation observed yet
- 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 GHSA-r7v4-jwx9-wx43.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-r7v4-jwx9-wx43 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
oauthenticatorReal-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
Background
CILogon is a federated auth provider that allows users to authenticate themselves via a number of Identity Providers (IdP), focused primarily on educational and research institutions (such as Universities). More traditional and open IdPs such as GitHub, ORCID, Google, Microsoft, etc are also supported.
CILogonOAuthenticator is provided by the OAuthenticator package, and lets users log
in to a JupyterHub via CILogon. This is primarily used to restrict a JupyterHub
only to users of a given institute. The allowed_idps configuration trait of
CILogonOAuthenticator is documented to be a list of domains that indicate the
institutions whose users are authorized to access this JupyterHub. This authorization
is validated by ensuring that the email field provided to us by CILogon has a
domain that matches one of the domains listed in allowed_idps.
Impact
If allowed_idps contains berkeley.edu, you might expect only users with valid
current credentials provided by University of California, Berkeley to be able to
access the JupyterHub. However, CILogonOAuthenticator does not verify which provider
is used by the user to login, only the email address provided. So a user can login
with a GitHub account that has email set to <something>@berkeley.edu, and that will
be treated exactly the same as someone logging in using the UC Berkeley official
Identity Provider. This has two consequences:
- Since GitHub (and most other providers we tested) only require you to verify your email once, a user can access a JupyterHub even if their access to the institution's IdP has been revoked or expired.
- CILogon supports hundreds of identity providers - if even one of them allows users to set any email ids without verifying, that can be used to impersonate any user on any other identity provider! While CILogon itself has a stellar security record, this particular method of doing authorization means an attacker would only need to compromise a single identity provider to compromise all of CILogon
We currently do not know of any identity provider that provides unverified email addresses to CILogon, so this is not a severe known vulnerability. However, there are hundreds of IdPs, and we could not try them all.
Patches
This patch makes a breaking change in how allowed_idps is interpreted. It's
no longer a list of domains, but configuration representing the EntityID of the
IdPs that are allowed, picked from the list maintained by CILogon.
So instead of berkeley.edu, you would specify urn:mace:incommon:berkeley.edu to
allow logins from users currently with berkeley.edu accounts. GitHub users
with a verified berkeley.edu email will no longer be allowed to log in.
For details on how to transition your CILogonOAuthenticator configuration to the patched version 15.0.0 or above, see the migration documentation.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | oauthenticator | all versions | 15.0.0pip install --upgrade 'oauthenticator==15.0.0' |
Detection & mitigation playbook
Open-source dependencyDetect
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 15.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r7v4-jwx9-wx43 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-r7v4-jwx9-wx43 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-r7v4-jwx9-wx43. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-r7v4-jwx9-wx43 in your dependencies?
O3 Security finds GHSA-r7v4-jwx9-wx43 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.