ZKTeco BioTime 8.5.5 through 9.x before 9.0.1 (20240617.19506) allows authenticated attackers to create or overwrite arbitrary files on the server via crafted requests to /base/sftpsetting/ endpoints that abuse a path traversal issue in the Username field and a lack of input sanitization on the SSH Key field. Overwriting specific files may lead to arbitrary code execution as NT AUTHORITY\SYSTEM.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.