The Simple User Registration plugin for WordPress suffers from a stored cross-site scripting vulnerability (CWE-79) due to improper neutralization of input in the 'wpr_admin_msg' parameter. This allows unauthenticated attackers to inject arbitrary web scripts that execute in the context of users viewing the injected pages. The vulnerability affects all versions up to and including 6.6. The CVSS 3.1 base score is 7.2, reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and impacts on confidentiality and integrity with scope changed. No patch or vendor advisory is currently available, and the plugin is not a cloud service.

Successful exploitation allows unauthenticated attackers to execute arbitrary scripts in the context of users visiting the affected pages, potentially leading to theft of sensitive information, session hijacking, or other malicious actions impacting confidentiality and integrity. Availability is not affected. No known exploits have been reported in the wild.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should consider disabling the plugin or restricting access to affected pages to trusted users only. Monitor official nmedia or WordPress security channels for updates. Avoid interacting with suspicious content related to this plugin.