Summary The patch that addressed CVE-2023-40581 attempted to prevent RCE when using –exec with %q by replacing double quotes with two double quotes. However, this escaping is not sufficient, and still allows expansion of environment variables. Support for output template expansion in –exec, along with this vulnerable behavior, was added to yt-dlp in version 2021.04.11. “`cmd yt-dlp "https://youtu.be/42xO6rVqf2E" –ignore-config -f 18 –exec "echo %(title)q" [youtube] Extracting URL: https://youtu.be/42xO6rVqf2E [youtube] 42xO6rVqf2E: Downloading webpage [youtube] 42xO6rVqf2E: Downloading ios player API JSON [youtube] 42xO6rVqf2E: Downloading android player API JSON [youtube] 42xO6rVqf2E: Downloading m3u8 information [info] 42xO6rVqf2E: Downloading 1 format(s): 18 [download] Destination: %CMDCMDLINE：~-1%&echo pwned&calc.exe [42xO6rVqf2E].mp4 [download] 100% of 126.16KiB in 00:00:00 at 2.46MiB/s [Exec] Executing command: echo "%CMDCMDLINE:~-1%&echo pwned&calc.exe" "" pwned “` Patches yt-dlp version 2024.04.09 fixes this issue by properly escaping %. It replaces them with %%cd:~,%, a variable that expands to nothing, leaving only the leading percent. Workarounds It is recommended to upgrade yt-dlp to version 2024.04.09 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: – Avoid using any…Read More