Next.js is a React framework for building full-stack web applications. From 16.0.0 until 16.3.8, Image Optimization can follow attacker-controlled DNS resolution for a remote URL that matches images.remotePatterns, allowing the optimized image fetch to reach private IP addresses after the URL passes the allow-list check. Applications without images.remotePatterns are not affected. Administrators unable to upgrade should audit allow-listed hosts and avoid entries whose DNS records are not trusted. This issue is fixed in version 16.3.8.