Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to 1.6.11, a path traversal in the website content subsystem lets an authenticated operator read arbitrary files on the Sliver server host. This is an authenticated path traversal / arbitrary file read issue, and it can expose credentials, configs, and keys. This vulnerability is fixed in 1.6.11.
Sliver from v1.5.x to v1.5.39 has an improper cryptographic implementation, which allows attackers to execute a man-in-the-middle attack via intercepted and crafted responses.