CVE-2025-12492 is a vulnerability classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) affecting the Ultimate Member WordPress plugin, which provides user profile, registration, login, member directory, content restriction, and membership management features. The flaw exists in the ajax_get_members function, which uses a predictable, low-entropy token to identify member directories. This token is a 5-character hexadecimal string derived from the MD5 hash of the post ID, resulting in a small token space of 16^5 (approximately 1 million possibilities). Because the AJAX endpoint lacks proper authorization checks and is accessible without authentication, attackers can enumerate or brute-force these tokens to extract sensitive user data. The exposed information includes usernames, display names, user roles (notably including administrator accounts), profile URLs, and user IDs. This data leakage can facilitate further attacks such as targeted phishing, privilege escalation attempts, or social engineering. The vulnerability affects all versions up to and including 2.11.0 of the plugin. The CVSS v3.1 base score is 5.3 (medium severity), reflecting the network attack vector, no required privileges or user interaction, and limited impact confined to confidentiality. No patches or known exploits are currently reported, but the vulnerability's characteristics make exploitation feasible with automated tools. The root cause is the combination of predictable token generation and missing authorization on a public AJAX endpoint, highlighting a design flaw in access control and token management within the plugin.

For European organizations, this vulnerability poses a significant privacy and security risk, especially for those relying on the Ultimate Member plugin for managing user profiles and memberships on WordPress sites. Exposure of usernames and user roles, including administrator accounts, can enable attackers to conduct targeted phishing campaigns, credential stuffing, or privilege escalation attacks. The leakage of profile URLs and user IDs further aids attackers in profiling users and crafting social engineering attacks. While the vulnerability does not directly impact system integrity or availability, the confidentiality breach can lead to reputational damage, regulatory non-compliance (e.g., GDPR violations due to unauthorized data exposure), and potential downstream attacks. Organizations in sectors with sensitive user data or high-profile membership sites (e.g., educational institutions, professional associations, or membership-based services) are particularly at risk. The ease of exploitation without authentication increases the threat level, as attackers do not need valid credentials or user interaction to extract data. This could lead to widespread data harvesting campaigns targeting European users, undermining trust in affected services.

1. Immediate mitigation should include restricting access to the ajax_get_members AJAX endpoint by implementing server-side access controls such as IP whitelisting or requiring authentication tokens to access the endpoint. 2. Monitor web server logs for unusual patterns indicative of token enumeration or brute-force attempts targeting the AJAX endpoint. 3. Disable or limit the use of the Ultimate Member plugin's member directory feature if feasible until a patch is released. 4. Engage with the plugin vendor or community to obtain or develop a patch that replaces the low-entropy token with a cryptographically secure, high-entropy identifier and enforces strict authorization checks on AJAX endpoints. 5. Conduct a thorough audit of user data exposure and review user roles to ensure no unnecessary privileges are assigned. 6. Educate site administrators about the risks of exposing sensitive information via public endpoints and encourage regular plugin updates. 7. Implement Web Application Firewall (WAF) rules to detect and block suspicious enumeration or brute-force activities targeting the plugin's AJAX endpoints. 8. Prepare incident response plans to address potential data exposure incidents stemming from this vulnerability.