Livebook notebooks allow the definition of file_entries, and when an attacker supplies a notebook with a URL‑type file entry whose name contains directory traversal, the application accepts the filename verbatim and writes the fetched content to that path. Because the name is not validated during import, the attacker controls both the destination and the file contents, enabling arbitrary file creation or overwrite on the server. The weakness is a classic path traversal (CWE‑23) that can compromise confidentiality, integrity, or availability by creating or modifying sensitive files that the Livebook process can write to.

This issue affects Livebook by livebook-dev. All releases from 0.11.0 up to, but not including, 0.18.7 and from 0.19.0 up to, but not including, 0.19.9 are vulnerable.

The CVSS score of 7 indicates a high‑severity vulnerability. Although the EPSS score is not available, the lack of a KEV listing suggests no known widespread exploitation yet, but the vulnerability can be abused by any user who opens a malicious notebook; no account is required on the target instance. The attack vector is local to the user who installs the notebook, so the attacker must supply the notebook, but the resulting file write can target server files within the Livebook process’s writeable directories.