GDPR Cookie Compliance WordPress Plugin Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the GDPR Cookie Compliance WordPress plugin, affecting versions through 4.15.6. The issue arises from inadequate input sanitization and output escaping, allowing authenticated attackers with administrator-level permissions to inject arbitrary scripts. This vulnerability is particularly concerning in multi-site installations where unfiltered_html has been disabled, as the injected scripts are executed when users access the affected pages.

Impact

Exploitation of this vulnerability allows for stored cross-site scripting, where injected scripts are executed in the context of the user viewing the page. This could lead to session hijacking, account takeover, or the creation of backdoor admin accounts.

Reproduction

To reproduce this vulnerability, an authenticated user with editor-level privileges can navigate to the plugin's settings page. Once there, they can inject malicious JavaScript into the 'Cookie Banner Content' field under 'Advanced' settings'. After saving the changes, the injected script will execute when the consent banner is displayed on the frontend.

Remediation

Users are advised to update the GDPR Cookie Compliance plugin to version 4.15.7 or later.