An issue was discovered in MediaWiki 1.32.x through 1.34.x before 1.34.4. LogEventList::getFiltersDesc is insecurely using message text to build options names for an HTML multi-select field. The relevant code should use escaped() instead of text().
https://lists.wikimedia.org/pipermail/mediawiki-l/2020-September/048488.html
https://lists.wikimedia.org/pipermail/mediawiki-l/2020-September/048480.html