Mailgun Subscriptions WordPress Plugin Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the Mailgun Subscriptions plugin for WordPress, affecting all versions up to and including 1.3.1. The vulnerability arises from inadequate input sanitization and output escaping of user-supplied attributes in the 'mailgun_subscription_form' shortcode. This flaw allows authenticated attackers with contributor-level access or higher to inject arbitrary scripts into pages, which are executed when users access the affected page.

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.

Reproduction

To reproduce this vulnerability, an authenticated user with contributor-level access or higher can use the 'mailgun_subscription_form' shortcode without proper sanitization. This can be done by injecting a script into the 'description' attribute of the shortcode, which will be executed when the page is viewed.

Remediation

Users are advised to update the Mailgun Subscriptions plugin to version 1.3.2 or later, where this vulnerability has been patched.