CVE-2023-40581 Information

Description

yt-dlp is a youtube-dl fork with additional features and fixes. yt-dlp allows the user to provide shell command lines to be executed at various stages in its download steps through the --exec flag. This flag allows output template expansion in its argument so that metadata values may be used in the shell commands. The metadata fields can be combined with the %q conversion which is intended to quote/escape these values so they can be safely passed to the shell. However the escaping used for cmd (the shell used by Python’s subprocess on Windows) does not properly escape special characters which can allow for remote code execution if --exec is used directly with maliciously crafted remote data. This vulnerability only impacts yt-dlp on Windows and the vulnerability is present regardless of whether yt-dlp is run from cmd or from PowerShell. Support for output template expansion in --exec along with this vulnerable behavior was added to yt-dlp in version 2021.04.11. yt-dlp version 2023.09.24 fixes this issue by properly escaping each special character. \n will be replaced by \r as no way of escaping it has been found. It is recommended to upgrade yt-dlp to version 2023.09.24 as soon as possible. Also always be careful when using –exec because while this specific vulnerability has been patched using unvalidated input in shell commands is inherently dangerous. For Windows users who are not able to upgrade: 1. Avoid using any output template expansion in –exec other than (filepath). 2. If expansion in –exec is needed verify the fields you are using do not contain \ | or &. 3. Instead of using –exec write the info json and load the fields from it instead.

Reference

https://github.com/yt-dlp/yt-dlp/releases/tag/2021.04.11 https://github.com/yt-dlp/yt-dlp/releases/tag/2023.09.24 https://github.com/yt-dlp/yt-dlp/commit/de015e930747165dbb8fcd360f8775fd973b7d6e https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-42h4-v29r-42qg https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.09.24.003044