HIGH
A use-after-free flaw was found in fs/userfaultfd.c in the Linux kernel before 4.13.6. The issue is related to the handling of fork failure when dealing with event messages. Failure to fork correctly can lead to a situation where a fork event will be removed from an already freed list of events with userfaultfd_ctx_put().
http://www.securityfocus.com/bid/102516
https://access.redhat.com/errata/RHSA-2018:0676
https://access.redhat.com/errata/RHSA-2018:1062
https://access.redhat.com/security/cve/CVE-2017-15126
https://bugzilla.redhat.com/show_bug.cgi?id=1523481
https://github.com/torvalds/linux/commit/384632e67e0829deb8015ee6ad916b180049d252
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.13.6
Source: MITRE
Published: 2018-01-14
Updated: 2018-05-07
Type: CWE-416
Base Score: 9.3
Vector: AV:N/AC:M/Au:N/C:C/I:C/A:C
Impact Score: 10
Exploitability Score: 8.6
Severity: HIGH
Base Score: 8.1
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 2.2
Severity: HIGH