FileRun up to and including version 2026.2.0 contains an OS command injection vulnerability that allows authenticated attackers to achieve remote code execution by uploading a file with a malicious filename containing shell command substitution sequences. The thumbnail generation system passes filenames wrapped in shell double-quotes directly to exec() without escapeshellarg() sanitization, allowing filenames such as $(PAYLOAD).mp4 to survive the filename sanitizer and be evaluated as shell commands when ffmpeg, ImageMagick, vips, or stl-thumb processes the file during thumbnail generation.