Cross-site scripting in dvankooten MC4WP: Mailchimp for WordPress
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the form response message post meta fields (e.g., 'text_subscribed', 'text_error') in all versions up to, and including, 4.12.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| dvankooten | MC4WP: Mailchimp for WordPress | up to 4.12.0 | — | No fix listed | CNA |
- MC4WP: Mailchimp for WordPress Vendordvankooten Affected up to 4.12.0 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-4561
- 2026-10-03 Alias added: GHSA-fm8w-hq2c-rg96
References
Other 5
- https://www.wordfence.com/threat-intel/vulnerabilities/id/641b739d-f888-4327-b1c5-c95de39ee011?source=cve
- https://plugins.trac.wordpress.org/browser/mailchimp-for-wp/trunk/includes/forms/class-form.php#L295
- https://plugins.trac.wordpress.org/browser/mailchimp-for-wp/trunk/includes/forms/class-form-element.php#L116
- https://plugins.trac.wordpress.org/browser/mailchimp-for-wp/trunk/includes/forms/class-form-manager.php#L104
- https://plugins.trac.wordpress.org/changeset/3491781/
More dvankooten vulnerabilities
- TI-2026-18342 SQL injection in dvankooten koko-analytics CVSS 3.1HIGH 8.4
- TI-2026-01464 MC4WP: Mailchimp for WordPress <= 4.11.1 - Missing Authorization to Unauthenticated Arbitrary Subscription Deletion CVSS 3.1MEDIUM 6.5
- TI-2024-08546 MC4WP: Mailchimp Top Bar <= 1.6.0 - Reflected Cross-Site Scripting CVSS 3.1MEDIUM 6.1
- TI-2017-13750 The mailchimp-for-wp plugin before 4.1.8 for WordPress has XSS via the return value of add_query_arg. CVSS 3.0MEDIUM 6.1
- TI-2016-08909 The mailchimp-for-wp plugin before 4.0.11 for WordPress has XSS on the integration settings page. CVSS 3.0MEDIUM 6.1
- TI-2024-09001 Social Sharing (by Danny) <= 1.3.7 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode CVSS 3.1MEDIUM 6.4
Sources
- CVE-2026-4561 · CVE Program
- CVE-2026-4561 · NVD
- FIRST EPSS
- GHSA-fm8w-hq2c-rg96 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences