What’s Vulnerable › Vulnerabilities
CVE-2018-18397
- Severity: medium (CVSS 5.5 v3.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2018-12-12 · updated 2026-06-17
- Weakness: CWE-863
Description
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: 14.04, 16.04, 18.04, 18.10
- Linux kernel: before 4.19.7 — fixed in 4.19.7
- RedHat Enterprise Linux Desktop: 7.0
- RedHat Enterprise Linux Server: 7.0
- RedHat Enterprise Linux Server Aus: 7.4, 7.6
- RedHat Enterprise Linux Server Eus: 7.4, 7.5, 7.6
- RedHat Enterprise Linux Server Tus: 7.4, 7.6
- RedHat Enterprise Linux Workstation: 7.0
- Red Hat OpenShift Container Platform 4.18: 3.11
- RedHat Virtualization Host: 4.0
How to fix
Upgrade to a fixed version: Linux kernel 4.19.7. Check the vendor advisory for mitigations.
References
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=29ec90660d68bbdd69507c1c8b4e33aa299278b1
- https://access.redhat.com/errata/RHBA-2019:0327
- https://access.redhat.com/errata/RHSA-2019:0163
- https://access.redhat.com/errata/RHSA-2019:0202
- https://access.redhat.com/errata/RHSA-2019:0324
- https://access.redhat.com/errata/RHSA-2019:0831
- https://bugs.chromium.org/p/project-zero/issues/detail?id=1700
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.87
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.7
- https://github.com/torvalds/linux/commit/29ec90660d68bbdd69507c1c8b4e33aa299278b1
- https://usn.ubuntu.com/3901-1/
- https://usn.ubuntu.com/3901-2/
Get alerted when CVE-2018-18397 or the next vulnerability affects your stack