A linux security update has been released for Debian GNU/Linux 9 Extended LTS to address several vulnerabilities.

Package	linux-5.10
Version	5.10.179-3~deb9u1 (stretch)
Related CVEs	CVE-2023-2156  CVE-2023-3390  CVE-2023-3610  CVE-2023-20593  CVE-2023-31248  CVE-2023-35001

Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service or information leaks.

CVE-2023-2156

It was discovered that a flaw in the handling of the RPL protocol
may allow an unauthenticated remote attacker to cause a denial of
service if RPL is enabled (not by default in Debian).

CVE-2023-3390

A use-after-free flaw in the netfilter subsystem caused by
incorrect error path handling may result in denial of service or
privilege escalation.

CVE-2023-3610

A use-after-free flaw in the netfilter subsystem caused by
incorrect refcount handling on the table and chain destroy path
may result in denial of service or privilege escalation.

CVE-2023-20593

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.

For details please refer to
<https://lock.cmpxchg8b.com/zenbleed.html> and
<https://github.com/google/security-research/security/advisories/GHSA-v6wh-rxpg-cmm8>.

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.

CVE-2023-31248

Mingi Cho discovered a use-after-free flaw in the Netfilter
nf_tables implementation when using nft_chain_lookup_byid, which
may result in local privilege escalation for a user with the
CAP_NET_ADMIN capability in any user or network namespace.

CVE-2023-35001

Tanguy DUBROCA discovered an out-of-bounds reads and write flaw in
the Netfilter nf_tables implementation when processing an
nft_byteorder expression, which may result in local privilege
escalation for a user with the CAP_NET_ADMIN capability in any
user or network namespace.

For Debian 9 stretch, these problems have been fixed in version 5.10.179-3~deb9u1.

We recommend that you upgrade your linux-5.10 packages.

Further information about Extended LTS security advisories can be found in the  dedicated section of our website.