CVE-2025-6987 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Advanced iFrame WordPress plugin developed by mdempfle. This vulnerability affects all versions up to and including 2025.5. The root cause is improper neutralization of input during web page generation, specifically insufficient sanitization and escaping of user-supplied attributes in the plugin's 'advanced_iframe' shortcode. Authenticated attackers with contributor-level access or higher can exploit this flaw by injecting malicious scripts into pages via the shortcode parameters. These scripts are then stored persistently and executed in the context of any user who visits the compromised page, potentially leading to session hijacking, privilege escalation, or other malicious actions. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting medium severity, with an attack vector of network (remote exploitation), low attack complexity, requiring privileges (contributor or above), no user interaction, and a scope change indicating that the vulnerability affects components beyond the initially vulnerable plugin. The impact primarily affects confidentiality and integrity, with no direct availability impact. No known exploits are currently reported in the wild, and no patches are listed at the time of publication. This vulnerability is significant because WordPress is widely used across Europe, and the Advanced iFrame plugin is popular for embedding external content responsively. The ability for relatively low-privileged users to inject persistent scripts poses a risk to site visitors and administrators alike, potentially enabling further compromise or data theft.

For European organizations, this vulnerability presents a moderate risk, especially for those relying on WordPress sites with the Advanced iFrame plugin installed. Exploitation could lead to unauthorized disclosure of sensitive information such as authentication tokens, personal data, or internal communications, violating GDPR requirements. The stored XSS could also facilitate phishing attacks or malware distribution to site visitors, damaging organizational reputation and trust. Since contributor-level access is required, insider threats or compromised contributor accounts could be leveraged to exploit this vulnerability. Public-facing websites of government agencies, educational institutions, and businesses using this plugin are particularly at risk. The scope change in the CVSS vector suggests that exploitation could affect other components or user privileges beyond the plugin itself, increasing the potential impact. Although no active exploits are known, the medium severity and ease of exploitation with low complexity warrant proactive mitigation to prevent future attacks.

European organizations should immediately audit their WordPress installations to identify the presence of the Advanced iFrame plugin and verify the version in use. Until an official patch is released, administrators should consider disabling the plugin or restricting contributor-level user permissions to trusted personnel only. Implementing a Web Application Firewall (WAF) with custom rules to detect and block suspicious shortcode attribute inputs can help mitigate exploitation attempts. Additionally, applying Content Security Policy (CSP) headers can reduce the impact of injected scripts by restricting script execution sources. Regularly monitoring logs for unusual shortcode usage or script injection patterns is recommended. Organizations should also educate contributors about the risks of injecting untrusted content and enforce strong authentication and access controls to minimize the risk of account compromise. Once a patch becomes available, prompt application is critical. Finally, consider employing security plugins that sanitize shortcode inputs or provide enhanced input validation as an interim protective measure.