CVE-2026-5809: wpForo Forum <= 3.0.2 - Authenticated (Subscriber+) Arbitrary File Deletion via 'data[body][fileurl]' Parameter

The wpForo Forum plugin for WordPress is vulnerable to Arbitrary File Deletion in versions up to and including 3.0.2. This is due to a two-step logic flaw: the topicadd() and topicedit() action handlers accept arbitrary user-supplied data[] arrays from $REQUEST and store them as postmeta without restricting which fields may contain array values. Because 'body' is included in the allowed topic fields list, an attacker can supply data[body][fileurl] with an arbitrary file path (e.g., wp-config.php or an absolute server path). This poisoned fileurl is persisted to the plugin's custom postmeta database table. Subsequently, when the attacker submits wpftcfdelete[]=body on a topicedit request, the addfile() method retrieves the stored postmeta record, extracts the attacker-controlled fileurl, passes it through wpforofixuploaddir() which only rewrites legitimate wpforo upload paths and returns all other paths unchanged, and then calls wpdeletefile() on the unvalidated path. This makes it possible for authenticated attackers, with subscriber-level access and above, to delete arbitrary files writable by the PHP process on the server, including critical files such as wp-config.