CVE-2025-15516 is a vulnerability identified in the All-in-One Video Gallery plugin for WordPress, specifically affecting versions 4.1.0 through 4.6.4. The root cause is a missing authorization check (CWE-862) in the ajax_callback_store_user_meta() function, which is responsible for handling AJAX requests to store user metadata. This flaw allows any authenticated user with at least Subscriber-level privileges to update arbitrary string-based user meta keys associated with their own account. Because the capability check is absent, the plugin does not verify whether the user has permission to modify these metadata fields, leading to unauthorized data modification. The vulnerability does not permit modification of other users' data or privilege escalation but can be leveraged to alter user profile data, potentially affecting application logic or user experience. The attack vector is network-based, requiring authentication but no user interaction. The CVSS v3.1 score of 4.3 (medium severity) reflects low complexity of attack and limited impact confined to integrity of user metadata. No known public exploits or patches are currently available, indicating the need for proactive mitigation. The vulnerability is particularly relevant for WordPress sites using this plugin, which is popular for embedding and managing video content.

For European organizations, the impact of CVE-2025-15516 is primarily on the integrity of user metadata within WordPress sites using the All-in-One Video Gallery plugin. While the vulnerability does not allow attackers to compromise confidentiality or availability, unauthorized modification of user meta can disrupt user profiles, personalization, or plugin-specific functionality. This could lead to inconsistent user experiences, potential bypass of application logic relying on user meta, or indirect impacts on business processes that depend on accurate user data. Organizations with customer-facing websites or internal portals using this plugin may face reputational risks if attackers manipulate user data. Additionally, if user meta is used in access control decisions or content delivery, this vulnerability could be leveraged for more complex attacks. The requirement for authenticated access limits exposure to users with at least Subscriber privileges, which may reduce risk in environments with strict user management. However, in large or public-facing WordPress sites where user registration is open, the risk increases. Given the widespread use of WordPress in Europe, especially among SMEs and content publishers, this vulnerability warrants attention to prevent potential misuse.

European organizations should take the following specific mitigation steps: 1) Immediately audit WordPress sites to identify installations of the All-in-One Video Gallery plugin and verify the version in use. 2) Restrict user registration and limit Subscriber-level accounts to trusted users only, reducing the pool of potential attackers. 3) Implement strict role-based access controls and monitor user activities for anomalous changes to user metadata. 4) Temporarily disable or restrict AJAX endpoints related to user meta updates if feasible, using web application firewalls or custom code. 5) Monitor plugin vendor communications for official patches or updates addressing this vulnerability and apply them promptly once available. 6) Conduct regular security assessments and penetration tests focusing on user privilege abuse scenarios. 7) Educate site administrators about the risks of unauthorized user meta modification and encourage strong authentication practices. 8) Consider deploying runtime application self-protection (RASP) or endpoint detection solutions to detect suspicious AJAX requests targeting user meta functions. These targeted actions go beyond generic advice by focusing on controlling user privileges, monitoring specific plugin behavior, and preparing for patch deployment.