My favorite bug class right now: **argument injection.** ๐ฏ
Jellyfin had an unauthenticated endpoint that could turn FFmpeg into a file reader.
๐ `/Videos/{itemId}/stream`
An unvalidated query parameter was passed straight into FFmpeg.
The trick wasn't `;id` or shell injection. โ
It was an `-vf drawtext` filter that made FFmpeg render `[/]etc[/]shadow` into the video response. ๐
โ No shell needed
โ No semicolon
๐ Just argument injection.