I recently ran Gossa on my home server using Docker, mounting it to a folder. Since I used rootless Docker, I was curious - if Gossa were to be a
virus, would I have been infected? Have any of you had experience with Gossa?
This is not true. Perhaps on an already at-risk or exploitable machine, but even then it's not trivial, and this is not a widespread thing that happens everywhere all the time
It is. Privilege escalation vulnerabilities are common. There is basically a 100% chance of unpatched container escapes in the Linux kernel. Some of these are very likely privately known and available for sale. So even if you are fully patched a resourceful attacker will escape the container.
That being said if you are a low-value regular-joe patching regularly, the risk is relatively low.
They might be talking about posts like this (which I would love to have refuted, as this kind of info has so far kept me from using Docker significantly):
Docker/Podman and LXC linux containers share the same kernel with the host machine. Root in the container is root period (in the case of rootfull containers). Even without root, much of the data on your machine is readable from any user. With a exploit to escape the container (which are common) the malicious program has root on the machine. This is a known attack vector against linux containers. VMs are much better for isolating untrusted software from the host OS.