A flaw was found in Next.js, a React framework. When self-hosting Next.js with the default image loader and configured to optimize remotely hosted images, a remote attacker could exploit the Image Optimization API. By providing malicious images, the attacker can cause CPU exhaustion, leading to a Denial of Service (DoS) in the /_next/image endpoints. This vulnerability specifically affects configurations using config.images.remotePatterns.

Next.js is a React framework for building full-stack web applications. In versions 15.5.0 through 15.5.20 and 16.0.0 through 16.2.10, when self-hosting Next.js with the default image loader, the Image Optimization API can optimize remotely hosted images if configured (not enabled by default). If those images contain malicious content, they can cause CPU exhaustion in /_next/image endpoints.Only config.images.remotePatterns is affected, and just the patterns in that array, whereas config.images.unoptimized: true, config.images.loader: 'custom', and Vercel are not impacted. This issue has been fixed in versions 15.5.21 and 16.2.11.

Next.js: Denial of Service in the Image Optimization API using SVGs