CVE-2025-5564 is a Stored Cross-Site Scripting (XSS) vulnerability identified in the GC Social Wall plugin for WordPress, developed by gurievcreative. This vulnerability affects all versions up to and including 1.15 of the plugin. The root cause is improper neutralization of input during web page generation, specifically insufficient sanitization and output escaping of user-supplied attributes within the plugin's 'gc_social_wall' shortcode. An authenticated attacker with contributor-level privileges or higher can exploit this flaw by injecting arbitrary malicious scripts into pages that utilize this shortcode. These scripts execute in the context of any user who views the compromised page, potentially leading to session hijacking, unauthorized actions, or theft of sensitive information. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting a medium severity level. The attack vector is network-based with low attack complexity, requiring privileges equivalent to contributor-level access but no user interaction to trigger the payload. The scope is changed, indicating that the vulnerability can affect resources beyond the initially compromised component. No known public exploits have been reported yet, and no official patches have been published at the time of this analysis. The vulnerability falls under CWE-79, which is a common and well-understood web application security weakness related to cross-site scripting attacks.

For European organizations, this vulnerability poses a significant risk primarily to websites and web applications using WordPress with the GC Social Wall plugin installed. Since WordPress is widely used across Europe for corporate, governmental, and small-to-medium enterprise websites, the potential impact includes unauthorized script execution leading to session hijacking, defacement, phishing, or data theft. The requirement for contributor-level access means that insider threats or compromised user accounts could be leveraged to exploit this vulnerability. The change in scope indicates that the attack could affect other components or users beyond the initially targeted page, potentially leading to broader compromise. Organizations in sectors with high web presence, such as e-commerce, media, and public services, are particularly at risk. Additionally, the lack of a patch increases exposure time. While the vulnerability does not directly affect availability, the integrity and confidentiality of user data and site content are at risk, which could damage reputation and lead to regulatory compliance issues under GDPR if personal data is compromised.

1. Immediate mitigation should include restricting contributor-level access to trusted users only, minimizing the risk of insider exploitation. 2. Implement strict input validation and output encoding at the application level, especially for any user-supplied content rendered via the 'gc_social_wall' shortcode, as a temporary workaround until an official patch is released. 3. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the vulnerable shortcode parameters. 4. Monitor logs for unusual activity from contributor accounts, including unexpected content changes or script injections. 5. Educate content contributors about the risks of injecting untrusted content and enforce content submission policies. 6. Regularly check for updates from the plugin vendor and apply patches promptly once available. 7. Consider disabling or replacing the GC Social Wall plugin if it is not essential to reduce attack surface. 8. Conduct security audits and penetration testing focusing on XSS vulnerabilities in WordPress environments to identify similar issues proactively.