Tavis Ormandy discovered that under specific microarchitectural
circumstances, a vector register in AMD "Zen 2" CPUs may not be
written to 0 correctly. This flaw allows an attacker to leak
sensitive information across concurrent processes, hyper threads
and virtualized guests.
This issue can also be mitigated by a microcode update through the amd64-microcode package or a system firmware (BIOS/UEFI) update.
However, the initial microcode release by AMD only provides
updates for second generation EPYC CPUs. Various Ryzen CPUs are
also affected, but no updates are available yet.
For the stable distribution (bookworm), this problem has been fixed in
We recommend that you upgrade your linux packages.