Fairphone 3 has an end-of-life Linux 4.9 kernel which hasn't been receiving updates for multiple years. They weren't shipping kernel updates even while they were available. Fairphone 4 and Fairphone 5 also have end-of-life kernels. Fairphone 6 kernel isn't end-of-life yet but they're not shipping the updates. This is a massive security problem for every Fairphone and it's very easy to exploit them due to it. There are publicly available exploits usable for those kernels.