GNU Mailman before 2.1.33 allows arbitrary content injection via the Cgi/private.py private archive login page.
lists.opensuse.org/opensuse-security-announce/2020-10/msg00047.html
lists.opensuse.org/opensuse-security-announce/2020-10/msg00063.html
bugs.launchpad.net/mailman/+bug/1877379
lists.debian.org/debian-lts-announce/2020/06/msg00036.html
lists.debian.org/debian-lts-announce/2020/07/msg00007.html
usn.ubuntu.com/4406-1/
www.debian.org/security/2021/dsa-4991