CVE-2026-1866 is a stored Cross-Site Scripting (XSS) vulnerability identified in the 'Name Directory' WordPress plugin developed by jeroenpeters1986, affecting all versions up to and including 1.32.0. The vulnerability stems from flawed input sanitization logic where the plugin's sanitization function calls html_entity_decode() before applying wp_kses(), a WordPress function designed to filter allowed HTML tags and attributes, and then calls html_entity_decode() again on output. This double decoding process allows attackers to bypass sanitization by encoding malicious scripts in a way that they are not properly neutralized. Attackers can exploit this by submitting crafted inputs via the public submission form parameters 'name_directory_name' and 'name_directory_description'. Since the plugin allows unauthenticated submissions, attackers do not need to authenticate to inject payloads. However, the malicious content only executes when an administrator approves the submission or if auto-publish is enabled, making the attack vector reliant on site configuration or administrator action. Once injected, the malicious scripts execute in the context of any user viewing the affected page, potentially leading to session hijacking, theft of sensitive information, defacement, or further exploitation such as delivering malware. The CVSS 3.1 score of 7.2 reflects a network attack vector, no privileges or user interaction required, and a scope change due to the impact extending beyond the vulnerable component. Although no known exploits are currently in the wild, the vulnerability's characteristics make it a significant risk for WordPress sites using this plugin. The lack of available patches at the time of publication increases urgency for mitigation through configuration changes and monitoring.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of web applications using the Name Directory plugin on WordPress. Exploitation could lead to unauthorized script execution in users' browsers, enabling session hijacking, credential theft, or unauthorized actions performed on behalf of users. This can result in data breaches, loss of customer trust, and potential regulatory non-compliance under GDPR due to exposure of personal data. The attack requires no authentication, increasing the attack surface, and can affect any visitor to the compromised pages. Organizations relying on this plugin for public-facing directories or user-generated content are particularly vulnerable. The reputational damage and operational disruption from defacement or malware distribution could be substantial. Additionally, the vulnerability could be leveraged as a foothold for further attacks within the network if administrative credentials are compromised. Given the widespread use of WordPress in Europe, the potential impact is broad, especially for sectors like government, education, and SMEs that often use community plugins without extensive security vetting.

Until an official patch is released, European organizations should take immediate steps to mitigate risk. First, disable or restrict the public submission form to prevent unauthenticated inputs or disable auto-publish functionality to ensure all submissions require manual approval. Implement strict review procedures for all user-generated content to detect and reject suspicious inputs. Employ Web Application Firewalls (WAFs) with custom rules to detect and block common XSS payload patterns, particularly those involving double-encoded HTML entities. Regularly audit and monitor logs for unusual submission patterns or script injections. Educate administrators about the risk and ensure they verify submissions carefully before approval. Once patches become available, prioritize updating the plugin to the fixed version. Additionally, consider deploying Content Security Policy (CSP) headers to reduce the impact of any injected scripts. Conduct periodic security assessments of WordPress plugins and maintain an inventory to quickly identify vulnerable components. Finally, ensure backups are current to enable rapid recovery if exploitation occurs.