Title: Path traversal 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-2020-27994 Author: Jack Misiura from The Missing Link Website: https://www.themissinglink.com.au Timeline: 2020-10-28 Disclosed to Vendor 2021-01-21 Vendor releases patched version 2021-08-02 Publication 1. Vulnerability Description SolarWinds Serv-U File Server through 15.2.1 does not correctly validate path information, allowing the disclosure of files and directories outside of the user's home directory via a specially crafted GET request. 2. PoC On a vulnerable Serv-U installation issue the following GET request to get a listing of files and directories above the user's directory: https:///Web Client/?Command=List&dir=\..\*.* The user *MUST* be locked to their directory, and only access granted must be the said directory. Directory listing must be enabled. If any of the above is not present, the exploit will not work. 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 themissinglink.com.au ​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.