Thorn SFTP gateway 3.4.x before 3.4.4 uses Pivotal Spring Framework for Java deserialization of untrusted data, which is not supported by Pivotal, a related issue to CVE-2016-1000027. Also, within the specific context of Thorn SFTP gateway, this leads to remote code execution.
https://help.thorntech.com/docs/sftp-gateway-gcp-3.0/gcp-java-deserialization-rce/