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Debian LTS Advisory DLA-3511-1                debian-lts@lists.debian.org
https://www.debian.org/lts/security/                   Jochen Sprickerhof
July 31, 2023                                 https://wiki.debian.org/LTS
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Package        : amd64-microcode
Version        : 3.20230719.1+deb10u1
CVE ID         : CVE-2023-20593
Debian Bug     : 1041863

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
https://lock.cmpxchg8b.com/zenbleed.html
https://github.com/google/security-research/security/advisories/GHSA-v6wh-rxpg-cmm8

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
https://www.amd.com/en/resources/product-security/bulletin/amd-sb-7008.html

For Debian 10 buster, this problem has been fixed in version
3.20230719.1+deb10u1. Additionally the update contains a fix
for CVE-2019-9836.

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:
https://security-tracker.debian.org/tracker/source-package/amd64-microcode

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS