net/netfilter/nfnetlink_cthelper.c in the Linux kernel through 4.14.4 does not require the CAP_NET_ADMIN capability for new, get, and del operations, which allows local users to bypass intended access restrictions because the nfnl_cthelper_list data structure is shared across all net namespaces.
http://www.securityfocus.com/bid/102117
https://access.redhat.com/errata/RHSA-2018:0654
https://access.redhat.com/errata/RHSA-2018:0676
https://access.redhat.com/errata/RHSA-2018:1062
https://patchwork.kernel.org/patch/10089373/
https://usn.ubuntu.com/3617-1/
https://usn.ubuntu.com/3617-2/
https://usn.ubuntu.com/3617-3/
https://usn.ubuntu.com/3619-1/
https://usn.ubuntu.com/3619-2/
https://usn.ubuntu.com/3620-1/
https://usn.ubuntu.com/3620-2/
https://usn.ubuntu.com/3632-1/
Source: MITRE
Published: 2017-12-07
Updated: 2019-10-03
Type: CWE-862
Base Score: 4.6
Vector: AV:L/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 3.9
Severity: MEDIUM
Base Score: 7.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 1.8
Severity: HIGH