Mediawiki 1.31 before 1.31.1, 1.30.1, 1.29.3 and 1.27.5 contains a flaw where contrary to the documentation, $wgRateLimits entry for 'user' overrides that for 'newbie'.
https://www.debian.org/security/2018/dsa-4301
https://phabricator.wikimedia.org/T169545
https://lists.wikimedia.org/pipermail/wikitech-l/2018-September/090849.html
https://access.redhat.com/errata/RHSA-2019:3813
https://access.redhat.com/errata/RHSA-2019:3238