XWiki Platform Flamingo Theme UI is a tool that allows customization and preview of any Flamingo-based skin. Starting with versions 6.2.4 and 6.3-rc-1, a possible cross-site scripting vector is present in the `FlamingoThemesCode.WebHomeSheet` wiki page related to the "newThemeName" form field. The issue is patched in versions 12.10.11, 14.0-rc-1, 13.4.7, and 13.10.3. The easiest available workaround is to edit the wiki page `FlamingoThemesCode.WebHomeSheet` (with wiki editor) according to the suggestion provided in the GitHub Security Advisory.