Upstream released ppp-2.4.7 which fixes a potential security vulnerability: http://marc.info/?l=linux-ppp&m=140764978420764 There's not much technical details about this issue at this time.
Created ppp tracking bugs for this issue: Affects: fedora-all [bug 1128749]
Upstream commit: https://github.com/paulusmack/ppp/commit/7658e8257183f062dc01f87969c140707c7e52cb
ppp-2.4.5-34.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.
ppp-2.4.5-33.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.
Statement: Red Hat Enterprise Linux 5 is now in Production 3 Phase of the support and maintenance life cycle. This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/. This issue affects the versions of ppp as shipped with Red Hat Enterprise Linux 6 and 7. Red Hat Product Security has rated this issue as having Moderate security impact. A future update may address this issue. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/clasification/.