A linux kernel security update has been released for Debian GNU/Linux 11 to address several vulnerabilities.

DSA 5402-1: linux security update

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Debian Security Advisory DSA-5402-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
May 13, 2023   https://www.debian.org/security/faq
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Package : linux
CVE ID : CVE-2023-0386 CVE-2023-31436 CVE-2023-32233

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

CVE-2023-0386

It was discovered that under certain conditions the overlayfs
filesystem implementation did not properly handle copy up
operations. A local user permitted to mount overlay mounts in user
namespaces can take advantage of this flaw for local privilege
escalation.

CVE-2023-31436

Gwangun Jung reported a a flaw causing heap out-of-bounds read/write
errors in the traffic control subsystem for the Quick Fair Queueing
scheduler (QFQ) which may result in information leak, denial of
service or privilege escalation.

CVE-2023-32233

Patryk Sondej and Piotr Krysiuk discovered a use-after-free flaw in
the Netfilter nf_tables implementation when processing batch
requests, which may result in local privilege escalation for a user
with the CAP_NET_ADMIN capability in any user or network namespace.

For the stable distribution (bullseye), these problems have been fixed in
version 5.10.179-1.

We recommend that you upgrade your linux packages.

For the detailed security status of linux please refer to its security
tracker page at:
  https://security-tracker.debian.org/tracker/linux

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