QuickShare File Server 1.2.1 contains a path traversal vulnerability in its FTP service due to improper sanitation of user-supplied file paths. Authenticated users can exploit this flaw by submitting crafted sequences to access or write files outside the intended virtual directory. When the "Writable" option is enabled (default during account creation), this allows attackers to upload arbitrary files to privileged locations such as system32, enabling remote code execution via MOF injection or executable placement.