Not really. Generally we use "Local Privilege Exploit" to describe an exploit that goes from a reasonably normal user privileges to root privileges.
And we don't usually worry about them, because an application with normal user privileges can already to so much damage.
But this exploit can be triggered from inside a tightly sandboxed process, such as firefox's isolated browser process. Which means the attacker now only needs to chain two exploits together: One javascript exploit to get local code execution in an isolated sandbox, and this one to jump all the rest of the way to kernel mode.
Which means, you should update both firefox, and your linux kernel.
Realistically, if you have a browser sandbox, the system LPE exploit gives you very little more. Everything interesting on a desktop system is accessible by the user account directly.
They are a security boundary. The fact that you need a vulnerability to escape them is proof of that. They just don't have a particularly high cost of escape because reachable kernel vulnerabilities are so common.
If you are given a shell with `docker run -it --rm alpine:3 sh`, can you read the /etc/shadow on the host without kernel exploit? Assuming the docker and kernel are sufficiently update-to-date (e.g. latest Docker on Debian Stable).
I don't think this would change anything even if it were true, which it is not. Running as root in a container opens up tons of footguns but it is not a path out of the container on its own.
My mistake, leaving out some adjective one could interpret as a misunderstanding of containers as an effective (etc.) security boundary. Fool me 100+ times and all that.
There must be at least a triple-digit number of CVEs by now demonstratimg that in practice containers are a thinner layer of security (perhaps not quite as thin as the classic recommendation of running SSH on a nonstandard port, but that might be leaning toward the safer side of analogies vs. malicious code!) rather than a boundary like virtualization (not perfect but a best practice for isolation).
Runpod, digital ocean's gpu cloud, and at least a few others use Linux containers for isolation between tenants (look at Wiz's blog post about the nvidia container toolkit bug; digitalocean just puts everyone in a massive k8s cluster)
And we don't usually worry about them, because an application with normal user privileges can already to so much damage.
But this exploit can be triggered from inside a tightly sandboxed process, such as firefox's isolated browser process. Which means the attacker now only needs to chain two exploits together: One javascript exploit to get local code execution in an isolated sandbox, and this one to jump all the rest of the way to kernel mode.
Which means, you should update both firefox, and your linux kernel.