The vulnerability arises because the import path for file entries in livebook notebooks does not validate or restrict the file entry names, allowing path traversal sequences. When a URL-type file entry is processed, the system resolves the file path beneath the session's temporary directory but does not ensure the resolved path remains within that directory, allowing directory traversal. Consequently, when the file content is fetched and written, it can be placed anywhere writable by the Livebook process. This can be triggered by a victim opening an attacker-crafted notebook, causing arbitrary file writes within their authenticated session. The affected versions are >=0.11.0 <0.18.7 and >=0.19.0 <0.19.9. No official patch or remediation level is provided in the advisory, and no known exploits in the wild are reported.

An attacker can cause arbitrary file writes on the victim's system running livebook by supplying a malicious notebook. This can lead to unauthorized file creation or modification anywhere the Livebook process has write permissions. The attack requires the victim to open the malicious notebook and trigger the file fetch, but no attacker authentication is needed. This could potentially be leveraged for further attacks depending on the victim environment and file write locations.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should avoid opening notebooks from untrusted sources, especially those containing URL-type file entries. Monitoring for updates from livebook-dev is recommended to apply any official fixes once released.