After ppp installation the pppd has 4511 privileges and belongs to 'root:root'. It would be better to have execution permission limited to the group members by default - there's a 'dialout' group which probably can be used for this purpose. It's not a problem to this by hand but every update will of course 'reset' all changes and this creates a potential security risk.
pppd is used also for PPPoE, PPPoA and PPTP connections, not just for dial-up.
These permissions have been used by all distros since the beggining of time (pppd security track record is fairly clean).
*** Bug 143011 has been marked as a duplicate of this bug. ***
Well the security track is fairly clean but not entirely spotless. As to the permissions: on Debian they're 4754 and ownership 'root:dip', and in RH 755 - there's no suid.
I don't want to say it's an extremely serious vulnerability but the proposed solution in not very complicated as well. Maybe the hardened team should be involved in this discussion?