Citizen skin vulnerable to stored XSS through multiple system messages

Summary

Multiple system messages are inserted into the CommandPaletteFooter as raw HTML, allowing anybody who can edit those messages to insert arbitrary HTML into the DOM.

Details

The messages are retrieved using the plain() output mode: https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/072e4365e9084e4b153eac62d3666566c06f5a49/resources/skins.citizen.commandPalette/components/CommandPaletteFooter.vue#L61-L66 currentTip is set to one of these messages: https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/072e4365e9084e4b153eac62d3666566c06f5a49/resources/skins.citizen.commandPalette/components/CommandPaletteFooter.vue#L69 currentTip is inserted as raw HTML (vue/no-v-html should not be ignored here): https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/072e4365e9084e4b153eac62d3666566c06f5a49/resources/skins.citizen.commandPalette/components/CommandPaletteFooter.vue#L3-L4

PoC

1. Edit citizen-command-palette-tip-commands, citizen-command-palette-tip-users, citizen-command-palette-tip-namespace and citizen-command-palette-tip-templates to <img src="" onerror="alert(1)"> (script tags don't work here due to the way the HTML is inserted)
2. Open the command palette

Impact

This impacts wikis where a group has the editinterface but not the editsitejs user right.