The Juniper MX Series routers with Junos 13.3R3 through 13.3Rx before 13.3R6, 14.1 before 14.1R4, 14.1X50 before 14.1X50-D70, and 14.2 before 14.2R2, when configured as a broadband edge (BBE) router, allows remote attackers to cause a denial of service (jpppd crash and restart) by sending a crafted PAP Authenticate-Request after the PPPoE Discovery and LCP phase are complete.
https://kb.juniper.net/InfoCenter/index?page=content&id=JSA10665