Description

nbgrader is a system for assigning and grading notebooks. Enabling frame-ancestors: 'self' grants any JupyterHub user the ability to extract formgrader content by sending malicious links to users with access to formgrader, at least when using the default JupyterHub configuration of `enable_subdomains = False`. #1915 disables a protection which would allow user Alice to craft a page embedding formgrader in an IFrame. If Bob visits that page, his credentials will be sent and the formgrader page loaded. Because Alice's page is on the same Origin as the formgrader iframe, Javasript on Alice's page has _full access_ to the contents of the page served by formgrader using Bob's credentials. This issue has been addressed in release 0.9.5 and all users are advised to upgrade. Users unable to upgrade may disable `frame-ancestors: self`, or enable per-user and per-service subdomains with `JupyterHub.enable_subdomains = True` (then even if embedding in an IFrame is allowed, the host page does not have access to the contents of the frame).

Classification

CVE ID: CVE-2025-23205

CVSS Base Severity: MEDIUM

CVSS Base Score: 6.9

Affected Products

Vendor: jupyter

Product: nbgrader

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.05% (probability of being exploited)

EPSS Percentile: 17.96% (scored less or equal to compared to others)

EPSS Date: 2025-02-15 (when was this score calculated)

References

https://github.com/jupyter/nbgrader/security/advisories/GHSA-fcr8-4r9f-r66m
https://github.com/jupyter/nbgrader/pull/1915
https://github.com/jupyter/nbgrader/commit/73e137511ac1dc02e95790d4fd6d4d88dab42325
https://jupyterhub.readthedocs.io/en/stable/explanation/websecurity.html#:~:text=frame-ancestors

Timeline