CVE-2026-14863: FileRun 2026.2.0 RCE via Thumbnail Generation Command Injection

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.