I'm on Ubuntu 22.04 (not Mint). In my case, I did not have the earlier-
mentioned 4 offending lines at the bottom of my cupsd.conf, but my
cupsd.conf did have "BrowseAddress @LOCAL".

It seems the change from 2.4.1op1-1-ubuntu4.12 to 2.4.1op1-1-ubuntu4.15
is *more* than just safely parsing invalid IPv6 addresses that have too
many ":" in them. A cupsd.conf that was accepted by 4.12 but contains
deprecated lines will be rejected by 4.15. (Comment #35 explains why.)

A *workaround* for users is to get a brand-new cupsd.conf:

  mv /etc/cups/cupsd.conf /etc/cups/cupsd.conf.previous
  apt reinstall cups-daemon

If you think you might have modified your cupsd.conf at some point in
the past, you can compare cupsd.conf.previous to cupsd.conf to look for
customizations to re-apply. My cupsd.conf was from 2017 (!), so the two
files were quite different. I could have simply removed my offending
"BrowseAddress @LOCAL" line to satisfy 4.15, but starting over with a
fresh cupsd.conf seemed like the better way to go.

I suspect many systems will similarly have an ancient cupsd.conf: it
seems cupsd.conf is *not* in cups-daemon.list nor cups-daemon.conffiles;
instead, cups-daemon.postinst checks whether cupsd.conf exists,
otherwise makes a copy of /usr/share/cups/cupsd.conf.default . This
seems to mean the system gets a pristine cupsd.conf only on the initial
install, but receives no subsequent changes on subsequent package
upgrades. In particular, even if the sys admin has made no changes to
their cupsd.conf, their version will remain unchanged even while
/usr/share/cups/cupsd.conf.default could be evolving. In particular, if
a system started on say Ubuntu 16.04, and was upgraded every two years,
and is currently on 22.04, it seems it would still have the cupsd.conf
from 16.04.

(Compare the behavior to package cups-browsed, wherein cups-browsed.conf
is indeed part of cups-browsed.list and cups-browsed.conffiles. During
"apt upgrade", when there is a newer cups-browsed.conf but I have
modified mine, I get queried to examine the diff and decide what to do.
Such a thing does not happen with cupsd.conf. It just stays stuck on the
ancient version.)

Should this method of handling cupsd.conf by the cups-daemon package be
considered a bug? Personally I prefer the approach taken by cups-
browsed.

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https://bugs.launchpad.net/bugs/2133207

Title:
  cups security update causes issues with invalid config file

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