Versions mentioned in the description apply to the upstream
Remediation section below for
Debian:9 relevant versions.
MediaWiki through 1.32.1 has Incorrect Access Control. Suppressed username or log in Special:EditTags are exposed. Fixed in 1.32.2, 1.31.2, 1.30.2 and 1.27.6.
mediawiki to version 1:1.27.7-1~deb9u1 or higher.