A simple test is to check exploit-db.com for vulnerabilities in this software:
In the case of deluge 1.3.15, there are two Denial of Service vulnerabilities, but no others listed. Depending on the requirements of the server you'd like to run this on, that may be an acceptable risk.
To be clear, this is only a limitation if running on Windows or MacOS. Packages for the newest version, 2.0.3 (2019-06), are available for multiple variants of Linux.