Review a full, realistic file the way you would in a real code review. Find the vulnerability, then choose the correct fix from several plausible-looking options — each wrong answer gets its own explanation.
This isn't a short snippet — it's a full file, the way you'd actually see it on the job. Review it, click the line you think is the issue, then pick the correct fix from four realistic options.
New challenges are added regularly. In the meantime, try the quick-fire Vulnerability Spotter quiz, or head back to the challenges hub.