An isc-dhcp update has been released for Debian GNU/Linux 10 LTS

DLA 3326-1: isc-dhcp update

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Debian LTS Advisory DLA-3326-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Bastian Blank
February 20, 2023   https://wiki.debian.org/LTS
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Package : isc-dhcp
Version : 4.4.1-2+deb10u3
Debian Bug : 1022969

Under not completely understood conditions, dhclient completely removes
IPv6 addresses from use and is unable to restore them.

For Debian 10 buster, this problem has been fixed in version
4.4.1-2+deb10u3.

We recommend that you upgrade your isc-dhcp packages.

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

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