[exim] Tainted arg 2 for mailman_transport transport command

Hi gang!

I've been running Mailman with exim4 for about 20 years now!
Yesterday, I upgraded my Debian to exim 4.96-3. Then I got hit by
this mailman problem. Log entry

| 2022-07-20 11:43:44 1oE87D-007hOf-2N ** nep-technicians@???
| R=mailman_router T=mailman_transport: Tainted arg 2 for mailman_transport
| transport command: 'nep-technicians'

The list nep-technicians seems to exist

root@darni ~ # exim -bt nep-technicians@???
nep-technicians@???
router = mailman_router, transport = mailman_transport

Downgrading exim to 4.96-1 does not seem to fix the issue. Here
is the transporter

root@darni /etc/exim4 # cat ./conf.d/transport/14_exim4-config_mailman
mailman_transport:
  driver  = pipe
  command = MM_WRAP \
          '${if def:local_part_suffix \
                {${sg{$local_part_suffix}{-(\\w+)(\\+.*)?}{\$1}}} \
                {post}}' \
          $local_part
  current_directory = MM_HOME
  home_directory    = MM_HOME
  user              = MM_UID
  group             = MM_GID

just what the instruction say ... Here is my router

root@darni /etc/exim4 # cat ./conf.d/router/114_exim4-config_mailman | grep -v ^\#
mailman_router:
  driver            = accept
  domains           = +mm_domains
  require_files     = MM_LISTCHK
  local_part_suffix_optional
  local_part_suffix = -admin     : \
         -bounces   : -bounces+* : \
         -confirm   : -confirm+* : \
         -join      : -leave     : \
         -owner     : -request   : \
         -subscribe : -unsubscribe
  transport         = mailman_transport

Here is my template, again with comments left out for brefty

root@darni /etc/exim4 # cat conf.d/main/template_14_exim4-config_mailman | grep -v ^\#
MM_HOME=/var/lib/mailman
MM_UID=list
MM_GID=list
domainlist mm_domains=lists.openlib.org
MM_WRAP=MM_HOME/mail/mailman
MM_LISTCHK=MM_HOME/lists/${lc::$local_part}/config.pck

A manual check of MM_LISTCHK suggests that nep-techncians
should be found since the config.pck is there.

root@darni ~ # ls /var/lib/mailman/lists/nep-technicians/config.pck
/var/lib/mailman/lists/nep-technicians/config.pck

What more to check?

--

Cheers,

  Thomas Krichel                  http://openlib.org/home/krichel
                                              skype:thomaskrichel