/options/mailman in GNU Mailman before 2.1.31 allows Arbitrary Content Injection.
https://www.debian.org/security/2021/dsa-4991
https://usn.ubuntu.com/4354-1/
https://mail.python.org/pipermail/mailman-announce/
https://lists.debian.org/debian-lts-announce/2020/07/msg00007.html
https://lists.debian.org/debian-lts-announce/2020/05/msg00007.html
https://code.launchpad.net/mailman
https://bugs.launchpad.net/mailman/+bug/1873722
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00063.html
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00047.html
http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00003.html
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00036.html