What the vulnerability does
01Description
The Single Mailchimp plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'single-mailchimp' shortcode in all versions up to, and including, 1.4. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes (autocomplete, label, placeholder, btn_text, success_msg, error_msg) which are concatenated directly into HTML output by the single_mailchimp() function in shortcodes.php. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
Explanation of Vulnerability in Simple Terms
02Summary
Single Mailchimp versions 1.4 and earlier contain a cross-site scripting vulnerability that allows authenticated users to inject malicious scripts affecting other users. The vulnerability has a changed scope, meaning the impact extends beyond the vulnerable component itself. An attacker with low-level account access can craft malicious input that executes in other users' browsers, potentially compromising their sessions or data.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that execute in other users' browsers, potentially stealing session data or performing actions on their behalf.
Potential impact on your site
04Site Impact
Authenticated users can inject scripts affecting other users' sessions and data; site integrity and user confidentiality are at risk.
Conditions required to exploit
05Prerequisites
Attacker must have a low-privilege account on the site; no user interaction required from the victim.
Key dates
06Disclosure timeline
May 27, 2026
CVE published
May 27, 2026
Record updated
