Impact

On Windows, the shared %PROGRAMDATA% directory is searched for configuration files (SYSTEMCONFIGPATH and SYSTEMJUPYTERPATH), which may allow users to create configuration files affecting other users.

Only shared Windows systems with multiple users and unprotected %PROGRAMDATA% are affected.

Mitigations

- upgrade to jupytercore>=5.8.1 (5.8.0 is patched but breaks jupyter-server) , or - as administrator, modify the permissions on the %PROGRAMDATA% directory so it is not writable by unauthorized users, or - as administrator, create the %PROGRAMDATA%\jupyter directory with appropriately restrictive permissions, or - as user or administrator, set the %PROGRAMDATA% environment variable to a directory with appropriately restrictive permissions (e.g. controlled by administrators or the current user)

Credit

Reported via Trend Micro Zero Day Initiative as ZDI-CAN-25932