/usr/share/doc/libxml-libxml-perl/examples/xmlns/badguy.xml is in libxml-libxml-perl 1.89+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | <A:B xmlns:A="http://D"><A:C xmlns:A="http://E"></A:C></A:B>
|