Executive brief
Jupyter Core, a foundational component used by Jupyter notebooks and interactive data science environments, searches shared Windows system directories for configuration files. On multi-user Windows systems with inadequately protected shared folders, a local user could create malicious configuration files that affect other users' Jupyter sessions, potentially compromising data access and integrity. This vulnerability only impacts shared Windows systems where multiple users have access to unprotected system directories.
Technical details
The vulnerability is an uncontrolled search path element (CWE-427) affecting Jupyter Core on Windows. The root cause is that the SYSTEM_CONFIG_PATH and SYSTEM_JUPYTER_PATH variables resolve to the shared %PROGRAMDATA% directory, which on multi-user Windows systems may be writable by unprivileged users. An attacker with local user privileges can create or modify configuration files in this shared directory; when another user (including administrators) runs Jupyter, those malicious configuration files are loaded, potentially allowing code execution or privilege escalation. The attack requires user interaction (another user launching Jupyter). The vulnerability affects all versions prior to 5.8.1; version 5.8.0 is patched but breaks compatibility with jupyter-server. Mitigation is available via upgrade to jupyter_core 5.8.1 or higher.
Affected products
- Jupyter jupyter-core < 5.8.1
Timeline
- 2025-06-04: disclosed
- 2025-06-04: patched: Version 5.8.1 released; 5.8.0 is patched but breaks jupyter-server