cross-site inclusion (XSSI) of files in jupyter-server

Impact

Improper cross-site credential checks on /files/ URLs could allow exposure of certain file contents, or accessing files when opening untrusted files via "Open image in new tab".

Patches

Jupyter Server 2.7.2

Workarounds

Use lower performance --ContentsManager.files_handler_class=jupyter_server.files.handlers.FilesHandler, which implements the correct checks.

References

Upstream patch for CVE-2019-9644 was not applied completely, leaving part of the vulnerability open.

Vulnerability reported by Tim Coen via the bug bounty program sponsored by the European Commission and hosted on the Intigriti platform.