CVE-2018-18397

Publication date 12 December 2018

Last updated 25 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

5.5 · Medium

Score breakdown

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.

From the Ubuntu Security Team

Jann Horn discovered that the userfaultd implementation in the Linux kernel did not properly restrict access to certain ioctls. A local attacker could use this possibly to modify files.

Status

Package Ubuntu Release Status
linux-aws 18.10 cosmic
Fixed 4.18.0-1011.13
18.04 LTS bionic
Fixed 4.15.0-1033.35
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-flo 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-hwe 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Fixed 4.15.0-1033.35~16.04.1
14.04 LTS trusty Not in release
linux-azure 18.10 cosmic
Fixed 4.18.0-1013.13
18.04 LTS bionic
Fixed 4.18.0-1013.13~18.04.1
16.04 LTS xenial
Fixed 4.15.0-1040.44
14.04 LTS trusty
Fixed 4.15.0-1040.44~14.04.1
linux 18.10 cosmic
Fixed 4.18.0-16.17
18.04 LTS bionic
Fixed 4.15.0-46.49
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-azure-edge 18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.18.0-1013.13~18.04.1
16.04 LTS xenial
Fixed 4.15.0-1040.44
14.04 LTS trusty Not in release
linux-euclid 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp 18.10 cosmic
Fixed 4.18.0-1007.8
18.04 LTS bionic
Fixed 4.15.0-1028.29
16.04 LTS xenial
Fixed 4.15.0-1028.29~16.04.1
14.04 LTS trusty Not in release
linux-gcp-edge 18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.18.0-1007.8~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-goldfish 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-grouper 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe 18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.18.0-16.17~18.04.1
16.04 LTS xenial
Fixed 4.15.0-46.49~16.04.1
14.04 LTS trusty Not in release
linux-hwe-edge 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Fixed 4.15.0-46.49~16.04.1
14.04 LTS trusty Not in release
linux-kvm 18.10 cosmic
Fixed 4.18.0-1008.8
18.04 LTS bionic
Fixed 4.15.0-1030.30
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-lts-trusty 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-utopic 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-vivid 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-wily 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty
Not affected
linux-maguro 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-mako 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-manta 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem 18.10 cosmic
Fixed 4.15.0-1034.39
18.04 LTS bionic
Fixed 4.15.0-1034.39
16.04 LTS xenial Ignored end of standard support, was needs-triage
14.04 LTS trusty Not in release
linux-oracle 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1009.11
16.04 LTS xenial
Fixed 4.15.0-1009.11~16.04.1
14.04 LTS trusty Not in release
linux-raspi2 18.10 cosmic
Fixed 4.18.0-1010.12
18.04 LTS bionic
Fixed 4.15.0-1032.34
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-snapdragon 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 5.5 · Medium
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

    • USN-3903-2
    • Linux kernel (HWE) vulnerabilities
    • 6 March 2019
    • USN-3901-1
    • Linux kernel vulnerabilities
    • 5 March 2019
    • USN-3901-2
    • Linux kernel (HWE) vulnerabilities
    • 5 March 2019
    • USN-3903-1
    • Linux kernel vulnerabilities
    • 6 March 2019

Other references