CVE-2025-13620 is a vulnerability classified under CWE-862 (Missing Authorization) affecting the roxnor Wp Social Login and Register Social Counter plugin for WordPress, specifically versions up to and including 3.1.3. The issue stems from three REST API routes: wslu/v1/check_cache/{type}, wslu/v1/save_cache/{type}, and wslu/v1/settings/clear_counter_cache, which are registered with a permission_callback set to __return_true. This means these endpoints do not enforce any capability checks or nonce validation, effectively allowing any unauthenticated user to invoke them. As a result, attackers can send crafted REST requests to clear or overwrite the social counter cache data maintained by the plugin. This manipulation can distort social login and registration metrics displayed on affected websites, potentially misleading site administrators or users relying on these counters for analytics or trust signals. The vulnerability does not expose confidential information nor does it allow denial of service, but it compromises data integrity. The CVSS v3.1 base score is 5.3, reflecting a medium severity due to network attack vector, no privileges or user interaction required, and limited impact on integrity only. No public exploits have been reported yet, but the ease of exploitation and lack of authentication make it a credible risk. The vulnerability was published on December 5, 2025, with no patches currently linked, indicating that users must apply manual mitigations or await vendor updates.

For European organizations, the primary impact of CVE-2025-13620 lies in the integrity of social login and registration metrics on WordPress sites using the vulnerable plugin. Manipulated social counters can undermine trustworthiness of social proof features, potentially affecting marketing analytics, user engagement assessments, and decision-making based on social login data. While this does not directly compromise sensitive user data or site availability, it can facilitate misinformation and reduce confidence in site metrics. Attackers could exploit this to skew analytics, disrupt marketing campaigns, or create reputational damage by falsifying social engagement indicators. Organizations relying heavily on social login features for user authentication or marketing in sectors like e-commerce, media, and online communities may experience indirect operational impacts. Given the plugin's WordPress integration, sites with high traffic or strategic importance in Europe could be targeted to influence public perception or user behavior. The lack of authentication requirement increases the risk of automated or widespread exploitation attempts.

To mitigate CVE-2025-13620, European organizations should: 1) Immediately audit WordPress sites for the presence of the roxnor Wp Social Login and Register Social Counter plugin and identify versions up to 3.1.3. 2) If vendor patches become available, apply them promptly. 3) In the absence of patches, implement web application firewall (WAF) rules to restrict access to the vulnerable REST API endpoints (wslu/v1/check_cache/{type}, wslu/v1/save_cache/{type}, wslu/v1/settings/clear_counter_cache) to trusted IP addresses or authenticated users only. 4) Disable or remove the plugin if it is not essential to reduce attack surface. 5) Monitor web server and application logs for unusual or repeated REST API calls targeting these endpoints, indicating potential exploitation attempts. 6) Consider adding custom authorization checks or nonce validation in the plugin code if feasible, to enforce proper permission controls. 7) Educate site administrators about the risks of missing authorization in REST endpoints and encourage regular plugin updates and security reviews. These steps go beyond generic advice by focusing on immediate access restrictions, monitoring, and code-level controls tailored to this specific vulnerability.