livebook-dev livebook up to 0.18.6/0.19.8 Import import.ex Name path traversal

Summaryinfo

A vulnerability labeled as problematic has been found in livebook-dev livebook up to 0.18.6/0.19.8. Affected is the function Livebook.LiveMarkdown.Import.file_entry_metadata_to_attrs of the file lib/livebook/live_markdown/import.ex of the component Import. Such manipulation of the argument Name leads to path traversal. This vulnerability is documented as CVE-2026-66881. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in livebook-dev livebook up to 0.18.6/0.19.8. It has been rated as problematic. Affected by this issue is the function Livebook.LiveMarkdown.Import.file_entry_metadata_to_attrs of the file lib/livebook/live_markdown/import.ex of the component Import. The manipulation of the argument name with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is integrity, and availability. CVE summarizes:

Relative Path Traversal vulnerability in livebook-dev livebook allows an attacker-authored notebook to write a file with attacker-controlled content to an arbitrary path. A .livemd notebook can declare file_entries metadata, each entry carrying a name. Every path that creates a file entry through the user interface validates that name with Livebook.Notebook.validate_file_entry_name/2, which requires a flat filename of alphanumerics, dashes, underscores and dots, ending in an extension. The import path does not: Livebook.LiveMarkdown.Import.file_entry_metadata_to_attrs/1 in lib/livebook/live_markdown/import.ex takes the name verbatim from the notebook source. For a URL-type file entry, Livebook.Session.file_entry_cache_file/2 in lib/livebook/session.ex resolves that name beneath the session's temporary directory without checking that the result stays inside it, and Livebook.FileSystem.Utils.resolve_unix_like_path/2 collapses parent-directory segments while clamping only at the filesystem root. When the entry's content is requested and no cached copy exists, Livebook fetches the entry's URL and writes the response body to the resolved path, creating parent directories as needed. The attacker therefore controls both the destination and the contents of the written file, which may land anywhere the Livebook process can write. The same missing containment check is present in Livebook.Session.to_attachment_file_entry/2. A victim who opens an attacker-supplied notebook and causes the entry to be fetched triggers the write within their own authenticated session; the attacker needs no account on the target instance. URL-type entries are also not placed under notebook stamping quarantine on import, so no warning is shown. This issue affects livebook: from 0.11.0 before 0.18.7 and from 0.19.0 before 0.19.9.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-66881 since 07/28/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 0.18.7 or 0.19.9 eliminates this vulnerability.

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Productinfo

Vendor

• livebook-dev

Name

• livebook

Version

• 0.18.0
• 0.18.1
• 0.18.2
• 0.18.3
• 0.18.4
• 0.18.5
• 0.18.6
• 0.19.0
• 0.19.1
• 0.19.2
• 0.19.3
• 0.19.4
• 0.19.5
• 0.19.6
• 0.19.7
• 0.19.8

Website

• Product: https://github.com/livebook-dev/livebook/

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