Title: Stored XSS Product: SolarWinds Serv-U FTP Server Vendor Homepage: https://www.solarwinds.com/ Vulnerable Version: 15.2.1 and lower Fixed Version: 15.2.2 CVE Number: CVE-2020-28001 Author: Jack Misiura from The Missing Link Website: https://www.themissinglink.com.au Timeline: 2020-10-30 Disclosed to Vendor 2021-01-21 Vendor releases patched version 2021-08-02 Publication 1. Vulnerability Description SolarWinds Serv-U FTP server through 15.2.1 does not correctly sanitize and validate the user-supplied directory names, allowing malicious users to create directories that when clicked on (in the breadcrumb menu) will trigger XSS payloads. 2. PoC On a vulnerable Serv-U FTP server installation, create a directory named as such: %27%29%3Ba%3Dfunction%28b%29%20%7B%20alert%28%22XSS%22%29%3B%20%7D%3Ba%28%27 The payload contains ');a=function(b) { alert("XSS"); };a(' As soon as a user clicks on the directory name in the breadcrumb menu, it will trigger the stored XSS. 3. Solution The vendor provides an updated version (15.2.2) which should be installed immediately. 4. Advisory URL https://www.themissinglink.com.au/security-advisories Jack Misiura​ Application Security Consultant a 9‑11 Dickson Avenue Artarmon NSW 2064 p 1300 865 865 os +61 2 8436 8585 w <https://www.themissinglink.com.au/> themissinglink.com.au <https://www.linkedin.com/company/the-missing-link-pty-ltd/> <https://www.facebook.com/The-Missing-Link-268395013346228/?ref=bookmarks> <https://twitter.com/TML_au> <https://www.youtube.com/channel/UC2kd4mDmBs3SjW4lX3fFHnQ> <https://www.instagram.com/the_missing_link_it/> <https://www.themissinglink.com.au/our-inclusive-culture> ​CAUTION - This message may contain privileged and confidential information intended only for the use of the addressee named above. If you are not the intended recipient of this message you are hereby notified that any use, dissemination, distribution or reproduction of this message is prohibited. If you have received this message in error please notify The Missing Link immediately. Any views expressed in this message are those of the individual sender and may not necessarily reflect the views of The Missing Link.