An OS command injection vulnerability in alseambusher/crontab-ui through 0.4.2 allows an unauthenticated remote attacker to execute arbitrary system commands by importing a crafted crontab database file. The POST /import endpoint accepts arbitrary .db files and overwrites the application database without validation. The hook field value is embedded directly into a shell command by crontab.js makeCommand() without sanitization, so a malicious hook value in the imported file results in command execution on the next cron execution cycle.