Smash Balloon Social Post Feed <= 4.13.0 - Unauthenticated Stored Cross-Site Scripting via Facebook Comment Message in Admin Builder Preview

The Smash Balloon Social Post Feed – Simple Social Feeds for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Facebook Comment Message via v-html in Admin Builder Preview in all versions up to, and including, 4.13.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that will execute whenever an administrator accesses the feed builder preview page. This attack requires only a Facebook account to post a comment on the connected Facebook Page, with no WordPress credentials needed; additionally, the use of v-show rather than v-if means injected HTML — including onerror handlers — is evaluated in the DOM even when the comment section is not visually displayed. When combined with the lack of URL validation in the cff_install_addon AJAX handler (admin/addon-functions.php), an injected script running in an administrator's session can trigger arbitrary plugin installation from an attacker-controlled URL, which may result in server-side code execution.