Oh joy, Spectre is back. New kernels are out to fix the new retbleed. Retbleed preys upon the fix for Spectre-2 that we all had fun with a few years ago.
Some people thought the retpoline wasn't enough of a fix and that returns could also be a target for these gadget & sidechannel attacks. Turns out they were right.
Unlike past vulns that were only, or worse, on Intel, this one is slightly worse on AMD.
Anyhow, early numbers predict a 12-25% slowdown of your box once you update and reboot. Joy indeed!
Info: just google retbleed