CVE-2025-46227 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the Brecht Custom Related Posts plugin up to version 1.7.4. This vulnerability arises due to improper neutralization of user-supplied input during web page generation, allowing malicious scripts to be injected and stored within the plugin's data. When a victim visits a compromised page, the malicious script executes in their browser context, potentially leading to session hijacking, credential theft, defacement, or redirection to malicious sites. Stored XSS is particularly dangerous because the payload persists on the server and affects all users accessing the infected content. The vulnerability is present in the way the plugin processes and outputs related post data without adequate sanitization or encoding. Although no public exploits are currently known in the wild and no official patches have been released, the medium severity rating reflects the potential for impactful exploitation if leveraged by attackers. The plugin is commonly used in WordPress environments to display related posts, meaning the attack surface includes websites running this plugin, which may range from personal blogs to corporate sites. The lack of a CVSS score limits precise quantification of risk, but the technical details confirm the vulnerability is exploitable without authentication, as it involves input that can be submitted via web forms or other user input mechanisms. The vulnerability was publicly disclosed on April 22, 2025, with enrichment from CISA, indicating recognition by cybersecurity authorities.

For European organizations, the impact of this Stored XSS vulnerability can be significant, especially for those relying on WordPress sites with the Brecht Custom Related Posts plugin installed. Exploitation could lead to compromise of user accounts, leakage of sensitive information, and erosion of trust in affected websites. Organizations in sectors such as finance, healthcare, e-commerce, and government, which often handle sensitive personal or financial data, may face regulatory repercussions under GDPR if user data confidentiality is breached. Additionally, attackers could use the vulnerability to distribute malware or conduct phishing campaigns targeting European users, amplifying the risk. The persistent nature of Stored XSS means that once exploited, the malicious script can affect all visitors until the vulnerability is remediated, potentially causing widespread damage. The medium severity suggests that while the vulnerability is serious, exploitation requires some level of user interaction (visiting the compromised page) but does not require authentication, increasing the risk profile. The absence of known exploits in the wild currently reduces immediate threat but does not eliminate future risk, especially as threat actors often weaponize such vulnerabilities rapidly after disclosure.

To mitigate this vulnerability, European organizations should first identify all WordPress installations using the Brecht Custom Related Posts plugin. Since no official patch is currently available, organizations should consider the following specific actions: 1) Temporarily disable or remove the Custom Related Posts plugin until a secure update is released. 2) Implement Web Application Firewall (WAF) rules that detect and block typical XSS payload patterns targeting the plugin's input fields. 3) Conduct thorough input validation and output encoding on any custom code interfacing with the plugin to prevent injection of malicious scripts. 4) Monitor website logs and user reports for unusual activity or complaints of suspicious behavior that may indicate exploitation attempts. 5) Educate site administrators and content contributors about the risks of injecting untrusted content and encourage strict content moderation. 6) Once a patch is released, prioritize immediate application of updates. 7) Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on affected web pages, reducing the impact of potential XSS payloads. These targeted measures go beyond generic advice by focusing on plugin-specific controls and compensating controls until official fixes are available.