SiteOrigin Widgets Bundle <= 1.74.3 - Authenticated (Contributor+) Arbitrary File Read via LESS Injection via [siteorigin_widget] Shortcode 'value' JSON Instance (design.colors LESS Variable)

The SiteOrigin Widgets Bundle plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 1.74.3 via the get_instance_css function. This makes it possible for authenticated attackers, with contributor-level access and above, to read the contents of arbitrary files on the server, which can contain sensitive information. The widget's normal update()/sanitize_field_input() pipeline — which would reject non-hex color values — is bypassed entirely because the [siteorigin_widget] shortcode handler calls $the_widget->widget() directly on the attacker-supplied decoded JSON instance.