Rocket.Chat has fixed a server-side path traversal vulnerability that may
be abused to write files to attacker-controlled locations:

https://github.com/RocketChat/Rocket.Chat/commit/f5c7d94bffb279d7a2f859773935fb5cf70c81cd

Exploitation of this vulnerability requires uploading attachments with
crafted names and requesting a data download.

No release of Rocket.Chat contains these fixes. Users should consider
cherrypicking f5c7d94bffb279d7a2f859773935fb5cf70c81cd to patch their
Rocket.Chat installation.