CVE-2026-9595

The CVE affects webpack-dev-server where a user-configured proxy with a broad context (e.g., /) and ws: true intercepts the dev server’s HMR WebSocket, forwarding it to the proxy target. This can leak cookies and Origin headers to the backend, bypass Host/Origin validation, and corrupt the HMR so...

CVE-2026-27977

CVE-2026-27977 affects the Next.js development server. The vulnerability lies in the Next.js dev mode where cross-site protection for internal HMR websocket endpoints could treat Origin: null as a permitted bypass even when allowedDevOrigins is configured, allowing privacy-sensitive contexts (e.g...

CVE-2026-27977 Next.js: null origin can bypass dev HMR websocket CSRF checks

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in next dev, cross-site protection for internal websocket endpoints could treat Origin: null as a bypass case even if allowedDevOrigins is configured, allowing...

CVE-2026-27977 Next.js: null origin can bypass dev HMR websocket CSRF checks

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in next dev, cross-site protection for internal websocket endpoints could treat Origin: null as a bypass case even if allowedDevOrigins is configured, allowing...