CVE-2025-15476 is a vulnerability identified in the WordPress plugin The Bucketlister, developed by simonfairbairn, affecting all versions up to and including 0.1.5. The root cause is a missing authorization check (CWE-862) in the bucketlister_do_admin_ajax() function, which handles AJAX requests for administrative actions. This flaw allows any authenticated user with at least Subscriber-level privileges to bypass capability checks and perform unauthorized modifications on bucket list items, including adding, deleting, or altering data. The vulnerability does not require elevated privileges beyond Subscriber, nor does it require user interaction beyond authentication. The CVSS v3.1 base score is 4.3 (medium), reflecting the network attack vector, low attack complexity, and limited impact confined to integrity without affecting confidentiality or availability. No patches or official fixes are currently available, and no known exploits have been reported in the wild. The vulnerability is significant because WordPress is widely used globally, and plugins like The Bucketlister are often installed on sites with multiple user roles, increasing the risk of unauthorized data manipulation by low-privileged users.

The primary impact of this vulnerability is unauthorized modification of bucket list data within affected WordPress sites. While it does not compromise confidentiality or availability, the integrity of data is at risk, which can undermine trust in the affected application and lead to misinformation or defacement. For organizations relying on The Bucketlister plugin for user-generated content or task tracking, this could result in data corruption or manipulation by low-privileged users, potentially affecting business processes or user experience. Since exploitation requires only Subscriber-level access, attackers could leverage compromised or created low-level accounts to escalate their influence within the site. Although no known exploits exist yet, the vulnerability's presence in a popular CMS ecosystem increases the likelihood of future exploitation attempts, especially in environments with weak user management policies.

1. Immediately restrict Subscriber-level user capabilities by implementing custom role management plugins or code to limit access to AJAX administrative functions related to The Bucketlister plugin. 2. Monitor and audit user activity logs for suspicious modifications to bucket list items, focusing on actions performed by low-privileged accounts. 3. Disable or uninstall The Bucketlister plugin if it is not essential to reduce the attack surface. 4. Apply virtual patching via Web Application Firewalls (WAFs) to block unauthorized AJAX requests targeting bucketlister_do_admin_ajax() endpoints from Subscriber-level users. 5. Engage with the plugin developer or community to obtain or contribute patches that introduce proper capability checks in the affected function. 6. Educate site administrators on the risks of granting Subscriber-level users unnecessary permissions and enforce strong authentication and account management policies. 7. Regularly update WordPress core and plugins to incorporate security fixes once available.