Title: Path traversal  
Product: SolarWinds Serv-U FTP Server  
Vendor Homepage:  
Vulnerable Version: 15.2.1 and lower  
Fixed Version: 15.2.2  
CVE Number: CVE-2020-27994  
Author: Jack Misiura from The Missing Link   
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://<serv-u host>/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    
Jack Misiura​  
Application Security Consultant  
9‑11 Dickson Avenue  
1300 865 865  
+61 2 8436 8585  
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