OpenEMR before 8.3.0 Arbitrary File Read and Write via FaxSMS disposeDocument

OpenEMR before 8.3.0 contains a path traversal vulnerability in the FaxSMS module's RCFaxClient and SignalWireClient disposeDocument functions that allows authenticated low-privilege users to read and overwrite arbitrary files via the unsanitized file_path parameter. Attackers can request action=download to retrieve cleartext files like sqlconf.php database credentials and keys, or use action=setup to overwrite web-server-writable files with ciphertext.