Debian Security Advisory

DSA-5459-1 amd64-microcode -- security update

Date Reported:
25 Jul 2023
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 1041863.
In Mitre's CVE dictionary: CVE-2023-20593.
More information:

Tavis Ormandy discovered that under specific microarchitectural circumstances, a vector register in Zen 2 CPUs may not be written to 0 correctly. This flaw allows an attacker to leak register contents across concurrent processes, hyper threads and virtualized guests.

For details please refer to

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. Fixes will be provided in a later update once they are released.

For more specific details and target dates please refer to the AMD advisory at

For the oldstable distribution (bullseye), this problem has been fixed in version 3.20230719.1~deb11u1. Additionally the update contains a fix for CVE-2019-9836.

For the stable distribution (bookworm), this problem has been fixed in version 3.20230719.1~deb12u1.

We recommend that you upgrade your amd64-microcode packages.

For the detailed security status of amd64-microcode please refer to its security tracker page at: