You would be surprised. A lot of cheap consumer routers are have two or four ARM cores. The bigger issue is that they are typically running a kernel from the stone age (< 6.0.0). Sometimes a still-supported LTS kernel like 5.10 or 5.15, but then they stopped at an old patch level.
Heck, apparently even the new Unifi UCG Fiber is running 5.4.213 (September 2022), but maybe they backport some fixes?
[1] https://community.ui.com/releases/dd0283dc-bf71-4140-ae1d-c1...
I’m in the market for a new router. Got a unifi u7 pro for wifi already, what are the options for routers? Sounds like the only safe thing is to roll your own so you can update things on time.
Note that even the latest OpenWRT is vulnerable to this, I'm running OpenWRT 25.12.6 and the kernel version is 6.12.112