kernel/ptrace.c in the Linux kernel through 4.4.1 mishandles uid and gid mappings, which allows local users to gain privileges by establishing a user namespace, waiting for a root process to enter that namespace with an unsafe uid or gid, and then using the ptrace system call. NOTE: the vendor states "there is no kernel bug here.
Exploitability
AV:LAC:HPR:LUI:NScope
S:UImpact
C:HI:HA:H7/CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H