ZArchiver, is this a secure safe app? Any risk with opening docs?

[Ashton2]

I'm opening encrypted password protected documents (an archive.7Z file on a cloud drive) on my phone using ZArchiver. It works as advertised.

I'm reading the docs using OfficeSuite. Is there any sort of security concern with ZArchiver, possibly storing or transmitting the opened doc to the outside world?

Any comments appreciated.