The vulnerability identified as CVE-2026-28559 affects the wpForo Forum plugin version 2.4.14 developed by gVectors Team. It is an information disclosure flaw that allows unauthenticated users to retrieve private and unapproved forum topics by exploiting the global RSS feed endpoint. Normally, privacy and status filters are applied when a forum ID parameter is included in the RSS feed request, restricting access to sensitive content. However, when the forum ID parameter is omitted, these filters are bypassed, allowing attackers to access restricted forum topics. This occurs because the SQL query or data retrieval logic does not enforce WHERE clauses for privacy and status without the forum ID, leading to unintended exposure of sensitive data. The vulnerability has a CVSS 4.0 score of 6.9, reflecting medium severity, with an attack vector of network (remote), no privileges or user interaction required, and limited impact confined to confidentiality. No known exploits have been reported in the wild, but the ease of exploitation and the nature of the data exposed make this a significant privacy risk for affected installations. The vulnerability is specific to version 2.4 of wpForo Forum, and users should verify their version and apply updates or mitigations accordingly.

The primary impact of CVE-2026-28559 is unauthorized disclosure of sensitive forum content, including private and unapproved topics. This can lead to leakage of confidential discussions, intellectual property, or sensitive user information, undermining user trust and potentially violating privacy regulations such as GDPR. Organizations relying on wpForo Forum for internal or community discussions may face reputational damage and legal consequences if sensitive data is exposed. Although the vulnerability does not affect data integrity or availability, the confidentiality breach alone can have serious consequences, especially for forums handling sensitive or proprietary information. Since exploitation requires no authentication and can be performed remotely, the attack surface is broad, increasing the risk of automated or targeted data harvesting. The absence of known exploits in the wild currently limits immediate widespread impact, but the vulnerability remains a significant risk until remediated.

To mitigate CVE-2026-28559, organizations should first verify the version of wpForo Forum in use and upgrade to a patched version once available from the vendor. In the absence of an official patch, administrators can implement the following specific mitigations: (1) Restrict access to the global RSS feed endpoint via web server or application firewall rules to allow only authenticated users or trusted IP ranges; (2) Modify or override the RSS feed query logic to enforce privacy and status filters regardless of the presence of the forum ID parameter; (3) Disable the global RSS feed feature temporarily if it is not essential to operations; (4) Monitor web server logs for unusual or repeated requests to the RSS feed endpoint without forum ID parameters, which may indicate exploitation attempts; (5) Educate forum administrators and users about the risk and encourage prompt reporting of suspicious activity. These targeted mitigations help reduce exposure until an official patch is applied.