CVE-2018-18397: Canonical Ubuntu Linux

Medium severity, CVSS 5.5. EPSS: 0.5% chance of exploitation in the next 30 days.

The userfaultfd implementation in the Linux kernel before 4.19.7 mishandles access control for certain UFFDIO_ ioctl calls, as demonstrated by allowing local users to write data into holes in a tmpfs file (if the user has read-only access to that file, and that file contains holes), related to fs/userfaultfd.c and mm/userfaultfd.c.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 18.04 only; version 18.10 only
• Linux Linux Kernel: before 4.19.7 (fixed in 4.19.7)
• Red Hat Enterprise Linux Desktop: version 7.0 only
• Red Hat Enterprise Linux Server: version 7.0 only
• Red Hat Enterprise Linux Server Aus: version 7.4 only; version 7.6 only
• Red Hat Enterprise Linux Server Eus: version 7.4 only; version 7.5 only; version 7.6 only
• Red Hat Enterprise Linux Server Tus: version 7.4 only; version 7.6 only
• Red Hat Enterprise Linux Workstation: version 7.0 only
• Red Hat Openshift Container Platform: version 3.11 only
• Red Hat Virtualization Host: version 4.0 only

Published 2018-12-12. Last modified 2026-06-17.