Jupyter Core is a package for the core common functionality of Jupyter projects. When using Jupyter Core prior to version 5.8.0 on Windows, the shared "%PROGRAMDATA%" directory is searched for configuration files ("SYSTEM_CONFIG_PATH" and "SYSTEM_JUPYTER_PATH"), which may allow users to create configuration files affecting other users. Only shared Windows systems with multiple users and unprotected "%PROGRAMDATA%" are affected. Users should upgrade to Jupyter Core version 5.8.0 or later to receive a patch. Some other mitigations are available. 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).