I've worked during October 2025 on the below listed packages, for
Freexian LTS/ELTS [1]

libpng1.6 (DLA-4396-1, ELA-1589-1, DSA-to-be-announced)
=======================================================

(This report inclusdes some foreshadowing for December)

libpng1.6 has reported several vulnerabilities; the upstream project
classified two of the four published vulnerabilities as high severity.

The task at hand was to update libpng1.6 across the full set of Debian
releases, coordinating with the security team to ensure the release of
the fixes was properly managed. Including LTS/ELTS, that meant fixing
six suites.

The fixes themselves where quite straightforward to backport to the
versions in Debian - libpng is quite a slow-moving mature project,
which helped a lot. 

However, the standard PNG library is literally used almost everywhere;
I think it is fair to say it's a key part of every operating system.
This, of course, requires a great deal of effort to ensure that the
update won’t break anything. I ran extensive testing on the update,
building reverse dependencies, using autopkgtests in those builds, and
also doing some manual testing in VMs. Some packages were too large for
Salsa’s CI, so I built those locally to make sure everything looked
fine.

(As a side note, Debusine was a huge help in these tasks, especially
for determining whether an autopkgtest failure was a regression or if
the package was already failing before.)

At the end of November I was getting ready to release the upload and
sent the security team all the debdiffs for review and upload coordination,
uploaded them to the security master for further processing.

In the meantime, I prepared all the other releases, ran them through
Debusine for final checks, and was about to upload… when the libpng
project reported a brand new CVE, assessed as high severity. It was
clear that this new CVE also needed to be addressed. I reached out to
the security team again, coordinated with them, and confirmed that they
agreed this vulnerability should be fixed as part of the same already-
prepared upload. So: rinse, lather, repeat -- backporting, preparing,
and testing again -- and now all six suites should be once again
prepared and safe soon.

Just when the updates were almost ready and well into testing, I noticed
a new email in my mailbox -- from the libpng's project announce mailing
list -- announcing yet another new upstream version. The email greeted
me with the introductory words: "... but it worked on my machine, and it
passed CI verification also!" For a second or two I feared that the
third time would be the charm.  Luckily, after reading the email, they
did not mean a broken update or new security fixes. So, finally, I was
able to release libpng to LTS/ELTS, and stable/oldstable will be
released by the security team shortly.

log4cxx
=======

Prepared the trixie stable-proposes-update to close 2 CVEs in stable
that have been previously been fixed in LTS. The has been included to
stable point release shortly after.


zabbix
======

Reached out to the security team how to handle zabbix for bookworm. (I'll
still need to follow up on that)



[1]  https://www.freexian.com/lts/ 
[2]  https://www.freexian.com/lts/debian/#sponsors

Cheers, 
-- 
tobi

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