CVE-2025-11926 is a stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, found in the Related Posts Lite plugin for WordPress developed by wpdreams. The vulnerability exists due to improper input sanitization and output escaping in the plugin's admin settings interface, allowing authenticated users with administrator-level privileges or higher to inject arbitrary JavaScript code. This malicious code is stored persistently and executed whenever any user visits the affected page, potentially compromising user sessions or redirecting users to malicious sites. The vulnerability affects all versions up to and including 1.12 and is specific to multi-site WordPress installations or those where the unfiltered_html capability is disabled, which restricts users from posting unfiltered HTML content. The CVSS 3.1 base score is 4.4, indicating a medium severity level, with the vector showing network attack vector (AV:N), high attack complexity (AC:H), requiring high privileges (PR:H), no user interaction (UI:N), and a scope change (S:C) with low confidentiality and integrity impacts (C:L/I:L) and no availability impact (A:N). No patches are currently linked, and no known exploits have been reported in the wild, but the vulnerability poses a risk primarily in environments where multiple sites are managed under a single WordPress installation and where administrative users might be compromised or malicious. Exploitation could lead to session hijacking, defacement, or further attacks leveraging the injected scripts.

For European organizations, this vulnerability presents a moderate risk primarily in multi-site WordPress environments using the Related Posts Lite plugin. If exploited, attackers with admin privileges could inject malicious scripts that execute in the browsers of site visitors or other administrators, potentially leading to session hijacking, unauthorized actions, or data leakage. Given the requirement for high privileges and the absence of user interaction, the attack surface is limited to trusted administrators, reducing the likelihood of widespread exploitation. However, in sectors such as government, finance, or healthcare where WordPress multi-site installations are common for managing multiple domains or departments, the impact could be significant if an insider threat or compromised admin account is involved. Additionally, the scope change in the CVSS vector indicates that the vulnerability could affect resources beyond the initially compromised component, increasing the risk of lateral movement within the affected WordPress environment. The lack of known exploits reduces immediate threat but does not eliminate future risk, especially as attackers often target popular CMS plugins. Organizations failing to address this vulnerability may face reputational damage, regulatory scrutiny under GDPR if personal data is exposed, and operational disruptions.

European organizations should implement the following specific mitigations: 1) Immediately audit all WordPress multi-site installations to identify the use of the Related Posts Lite plugin and verify the version in use. 2) Restrict administrator-level access strictly to trusted personnel and enforce strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. 3) Temporarily disable or remove the Related Posts Lite plugin in multi-site environments until a security patch or update is released by the vendor. 4) Monitor administrative actions and logs for suspicious activity related to plugin settings changes that could indicate attempted exploitation. 5) Implement Content Security Policy (CSP) headers to limit the impact of potential XSS payloads by restricting script sources. 6) Educate administrators about the risks of stored XSS and the importance of cautious input handling. 7) Regularly update WordPress core and plugins to the latest versions once patches become available. 8) Consider deploying web application firewalls (WAFs) with custom rules to detect and block malicious script injections targeting this plugin. These measures go beyond generic advice by focusing on access control, monitoring, and temporary mitigation until vendor patches are available.