An issue was discovered in the AbuseFilter extension in MediaWiki through 1.36. If the MediaWiki:Abusefilter-blocker message is invalid within the content language, the filter user falls back to the English version, but that English version could also be invalid on a wiki. This would result in a fatal error, and potentially fail to block or restrict a potentially nefarious user.
{
"cpes": [
"cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*"
],
"severity": "Critical"
}