Next.js URL Redirection to Untrusted Site (Open Redirect) Vulnerability - CVE-2026-64645

Next.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10 a rewrites() or redirects() rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname regardless of the rule39s hostname suffix. For a rewrite Next.js proxies the request to that arbitrary host and serves the response from the application39s origin leading to Server-Side Request forgery. A redirects() rule configured this way is vulnerable to an Open Redirect. This issue has been fixed in versions 15.5.21 and 16.2.11.