The Auth0 Next.js SDK is a library for implementing user authentication in Next.js applications. In Auth0 Next.js SDK versions 4.0.1 through 4.6.0, `__session` cookies set by auth0.middleware may be cached by CDNs due to missing Cache-Control headers. Three preconditions must be met in order for someone to be affected by the vulnerability: Applications using the NextJS-Auth0 SDK, versions between 4.0.1 to 4.6.0, applications using CDN or edge caching that caches responses with the Set-Cookie header, and if the Cache-Control header is not properly set for sensitive responses. Users should upgrade auth0/nextjs-auth0 to v4.6.1 to receive a patch.