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

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 privacy-sensitive/opaque contexts (for example sandboxed documents) to connect unexpectedly. If a dev server is reachable from attacker-controlled content, an attacker may be able to connect to the HMR websocket channel and interact with dev websocket traffic. This affects development mode only. Apps without a configured `allowedDevOrigins` still allow connections from any origin. The issue is fixed in version 16.1.7 by validating `Origin: null` through the same cross-site origin-allowance checks used for other origins. If upgrading is not immediately possible, do not expose `next dev` to untrusted networks and/or block websocket upgrades to `/_next/webpack-hmr` when `Origin` is `null` at the proxy.

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CWE-1385

Next.js 安全漏洞

Next.js是Vercel开源的一个 React 框架。 Next.js 16.0.1至16.1.7之前版本存在安全漏洞，该漏洞源于开发模式下内部WebSocket端点的跨站点保护可能将Origin: null视为绕过情况，可能导致攻击者连接到HMR WebSocket通道。

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