VOMIT (go/vomit) has received an external vulnerability report for the Linux kernel. 

Advisory: CVE-2018-18955
  Details: http://vomit.googleplex.com/advisory?id=CVE/CVE-2018-18955
  CVSS severity score: 4.4/10.0
  Description:

In the Linux kernel 4.15.x through 4.19.x before 4.19.2, map_write() in kernel/user_namespace.c allows privilege escalation because it mishandles nested user namespaces with more than 5 UID or GID ranges. A user who has CAP_SYS_ADMIN in an affected user namespace can bypass access controls on resources outside the namespace, as demonstrated by reading /etc/shadow. This occurs because an ID transformation takes place properly for the namespaced-to-kernel direction but not for the kernel-to-namespaced direction.



This bug was filed by http://go/vomit
Please contact us at vomit-team@google.com if you need any assistance.