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MC4WP vulnerabilities
MC4WP has 8 known vulnerabilities in this database. The most recent published record is dated 19 Sep 2026.
- Known vulnerabilities
- 8
- Active installs
- 1m+
- Latest version
- 4.14.1
- Last updated
- 16 Sep 2026
- Most recent
- 19 Sep 2026
Find it in your WordPress dashboard under Plugins. Severity is based on the CVSS score published with the CVE where one is available.
| Vulnerability | Severity | Affected | Fix | Published |
|---|---|---|---|---|
| Cross-site scripting (XSS) CVE-2026-87917 | Medium 6.1 | Up to 4.14.0 | Fixed in a later version (latest 4.14.1) | 19 Sep 2026 |
| Cross-site scripting (XSS) CVE-2026-4561 | Medium 6.4 | Up to 4.12.0 | Fixed in a later version (latest 4.14.1) | 22 Aug 2026 |
| Broken access control CVE-2026-1781 | Medium 6.5 | Up to 4.11.1 | Fixed in a later version (latest 4.14.1) | 11 Mar 2026 |
| Cross-site scripting (XSS) CVE-2024-8680 | Medium 4.4 | Before 4.9.17 | Fixed in 4.9.17 | 21 Sep 2024 |
| Cross-site scripting (XSS) CVE-2024-8850 | Medium 6.1 | Up to 4.9.16 | Fixed in a later version (latest 4.14.1) | 19 Sep 2024 |
| Cross-site scripting (XSS) CVE-2021-36833 | Medium 4.8 | Up to 4.8.6 | Fixed in a later version (latest 4.14.1) | 20 May 2022 |
| Cross-site scripting (XSS) CVE-2017-18577 | Medium 6.1 | Before 4.1.8 | Fixed in 4.1.8 | 22 Aug 2019 |
| Cross-site scripting (XSS) CVE-2016-10871 | Medium 6.1 | Before 4.0.11 | Fixed in 4.0.11 | 13 Aug 2019 |
Read the published descriptions
- CVE-2026-87917, 19 Sep 2026
- The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via 'data' Dynamic Content Tag in all versions up to, and including, 4.14.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. CVE record
- CVE-2026-4561, 22 Aug 2026
- 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. CVE record
- CVE-2026-1781, 11 Mar 2026
- The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 4.11.1. This is due to the plugin trusting the `_mc4wp_action` POST parameter without validation, allowing unauthenticated attackers to force the form to process unsubscribe actions instead of subscribe actions. This makes it possible for unauthenticated attackers to arbitrarily unsubscribe any email address from the connected Mailchimp audience via the `_mc4wp_action` parameter, granted they can obtain the form ID (which is publicly exposed in the HTML source). CVE record
- CVE-2024-8680, 21 Sep 2024
- The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via admin settings in all versions up to, and including, 4.9.16 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled. CVE record
- CVE-2024-8850, 19 Sep 2024
- The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'email' parameter when a placeholder such as {email} is used for the field in versions 4.9.9 to 4.9.16 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. CVE record
- CVE-2021-36833, 20 May 2022
- Authenticated (admin or higher user role) Stored Cross-Site Scripting (XSS) vulnerability in ibericode's MC4WP plugin <= 4.8.6 at WordPress. CVE record
- CVE-2017-18577, 22 Aug 2019
- The mailchimp-for-wp plugin before 4.1.8 for WordPress has XSS via the return value of add_query_arg. CVE record
- CVE-2016-10871, 13 Aug 2019
- The mailchimp-for-wp plugin before 4.0.11 for WordPress has XSS on the integration settings page. CVE record
What to do if you run MC4WP
If you run MC4WP, open WordPress and check the installed version in Plugins. Compare it with the affected versions in the vulnerability record. If a fixed version is available, take a current backup and update to that version or the latest supported release.
If no fixed version exists, consider disabling and removing the plugin or replacing it with a maintained alternative. After dealing with the affected software, check administrator users, unexpected file changes, redirects, unfamiliar pages and security logs for signs that the site may already have been altered.
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