AIKIDO-2026-685250

TL;DR

jekyll-remote-theme accepts a local filesystem path for remote_theme (anything starting with /, ./, ../, ~/, or a drive letter), resolves it with File.expand_path, and only checks Dir.exist? without confining it to the site source. The plugin runs from Jekyll's :after_reset hook, so this happens even when the site is built with safe: true. A _config.yml that sets remote_theme to an absolute or ../ path makes the builder use that directory as the theme root, so its _includes, _layouts, _data, and assets are read into the build and copied into _site, disclosing any file the build user can read on a host that compiles untrusted sites. The fix rejects local theme paths when the site is in safe mode or its safe setting is unknown.