Description
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.
References3
Metrics
- CVSS 3.1
-
6.4
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N - EPSS — exploit probability
- 0% percentile: 15 · as of 14 November 2026
- CWE
- CWE-79
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.