[exim] Problem with system_filter - Taint mismatch, string_…

Hi !

This is my first post to this mailing list, so I hope I am doing this
right :)

[My problem] : I have a small filter, that I added in system_filter, and
that following upgrade to 4.94, it doesn't work anymore.

[The goal of the filter] : To count the total amount of address in the
$h_to and $h_cc combined, per message, and do an appropriate action
following the results, such as success or fail.

[Note] : I have shorten the sample code, and used 'domain.com' and
`user1@???` and `user2@???` for the matter of testing and
demonstration, please change accordingly. Of course I would implement a
less 'hard coded' solution, but I need to get this to work before
implementing more complex solution, this is the most simple form I could
come up with that is still throwing an error, and add a paniclog such as :

2020-06-22 04:49:02 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc
1jnI8T-000JTg-VM
2020-06-22 04:49:02 1jnI8T-000JTg-VM Taint mismatch, string_nextinlist:
expand_string_internal 7213

[ Filter sample that do an error in 4.94 but not previous version such
as 4.93.0.4] :

if (
${listcount:${filter{${addresses:$h_to:,$h_cc:}}{!eq{"${domain:$item}"}{"domain.com"}}}}
is above 3 ) and
( "${domain:$sender_address}" is "domain.com" ) and
( "${local_part:$sender_address}" does not match "^(user1|user2)" )
then
        fail "WARNING - PLEASE USE THE \"BCC\" FIELD INSTEAD OF \"TO\"
FIELD OR \"CC\" FIELD. (LIMIT = 1)\n\n"
        seen finish
endif


I would appreciate any kind of help pointing me in the right direction,
so that I can keep my exim up to date. I understand that there might has
been change that break this code, that fine to me, I just need a bit of
help because I have servers that I need to keep up to date, and I had to
disable auto-update on a few due to that...  I have seen some other
tainted mismatch error from others since 4.94, but none like mine.

Thank you in advance.

Steve A,