Is MC4WP safe to use?

Laskyr does not give safety verdicts. No known unpatched vulnerabilities in the latest version (4.14.1). As of 2026-11-01. 9 issues are on record for older versions; version 4.14.1 or newer fixes all of them that state a fix. Keep MC4WP on the latest version (4.14.1) and remove it if you do not use it.

Which versions of MC4WP are vulnerable?

Known issues on record (newest first): Reflected cross-site scripting (XSS) (4.14.0 and older, fixed in 4.14.1); Stored cross-site scripting (XSS) (4.12.0 and older, fixed in 4.12.1); Missing authorization check (4.11.1 and older, fixed in 4.12.0); Stored cross-site scripting (XSS) (4.9.16 and older, fixed in 4.9.17); Reflected cross-site scripting (XSS) (4.9.9 to 4.9.16, fixed in 4.9.17); Missing authorization check (4.9.9 and older, fixed in 4.9.10). The full list with sources is on this page.

What is the latest version of MC4WP?

4.14.1, according to wordpress.org (last updated 2026-09-16). It has 1+ million active installs.

What should I do if my MC4WP is out of date?

Take a backup, then update it from Dashboard > Updates (or run wp plugin update mailchimp-for-wp). If you cannot update right away, deactivate it until you can. If you think the site was already attacked, run a free scan at https://laskyr.com/scan.

Plugins · mailchimp-for-wp · data as of 2026-11-01

Is MC4WP safe? Known vulnerabilities and latest version

Latest version: 4.14.1
Last updated: 2026-09-16
Active installs: 1+ million
Known issues on record: 9
Unpatched in latest: 0
Tested up to WP: 7.1.4 · PHP 7.4+

The #1 Mailchimp plugin for WordPress. Allows you to add a multitude of newsletter sign-up methods to your site. — by Danny van Kooten

What to do

Update to the latest version (4.14.1). Anything older than 4.14.1 has at least one known issue listed below. Dashboard → Updates, or Plugins → “update now”.
If you cannot update right away, deactivate it until you can.
Turn on auto-updates for it: Plugins → “Enable auto-updates” on its row.
If you ran a vulnerable version and something looks off (spam pages, strange admins, redirects), run the free scan.

With WP-CLI: wp plugin get mailchimp-for-wp --field=version shows what you run; wp plugin update mailchimp-for-wp updates it.

Check your version

Known vulnerabilities

9 on record, newest first. “Affected” is the version range the source gives; “fixed in” is the version the source names, or (marked *) the first wordpress.org release after the last affected version.

medium 6.1 CVE-2026-87917 · published 2026-09-19

Reflected cross-site scripting (XSS) in MC4WP (4.14.0 and older)

Affected: 4.14.0 and older
Fixed in: 4.14.1 *
Access needed (per CVSS): No login needed; someone on the site has to click a link or open a page
Range from: CVE record (the advisory publisher) · score by Wordfence

Details from the advisory

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.

NVD CVE-2026-87917 Wordfence advisory Code change (fix)Plugin source

medium 6.4 CVE-2026-4561 · published 2026-08-22

Stored cross-site scripting (XSS) in MC4WP (4.12.0 and older)

Affected: 4.12.0 and older
Fixed in: 4.12.1 *
Access needed (per CVSS): Needs a low-level account (e.g. subscriber)
Range from: CVE record (the advisory publisher) · score by Wordfence

Details from the advisory

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.

NVD CVE-2026-4561 Wordfence advisory Code change (fix)Plugin source

medium 6.5 CVE-2026-1781 · published 2026-03-11

Missing authorization check in MC4WP (4.11.1 and older)

Affected: 4.11.1 and older
Fixed in: 4.12.0 *
Access needed (per CVSS): No login needed
Range from: CVE record (the advisory publisher) · score by Wordfence

Details from the advisory

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).

NVD CVE-2026-1781 Wordfence advisory Code change (fix)cwe.mitre.org github.com Plugin source

medium 5.5 CVE-2024-8680 · published 2024-09-21

Stored cross-site scripting (XSS) in MC4WP (4.9.16 and older)

Affected: 4.9.16 and older
Fixed in: 4.9.17 *
Access needed (per CVSS): Needs an admin-level account
Range from: CVE record (the advisory publisher) · score by NVD

Details from the advisory

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.

NVD CVE-2024-8680 Wordfence advisory Code change (fix)github.com github.com Plugin source

medium 6.1 CVE-2024-8850 · published 2024-09-19

Reflected cross-site scripting (XSS) in MC4WP (4.9.9 to 4.9.16)

Affected: 4.9.9 to 4.9.16
Fixed in: 4.9.17 *
Access needed (per CVSS): No login needed; someone on the site has to click a link or open a page
Range from: CVE record (the advisory publisher) · score by Wordfence

Details from the advisory

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.

NVD CVE-2024-8850 Wordfence advisory Code change (fix)Plugin source

medium 5.3 CVE-2023-51682 · published 2024-06-11

Missing authorization check in MC4WP (4.9.9 and older)

Affected: 4.9.9 and older
Fixed in: 4.9.10
Access needed (per CVSS): No login needed
Range from: CVE record (the advisory publisher) · score by NVD

Details from the advisory

Missing Authorization vulnerability in ibericode MC4WP.This issue affects MC4WP: from n/a through 4.9.9.

NVD CVE-2023-51682 Patchstack advisory

medium 4.8 CVE-2021-36833 · published 2022-05-20

Stored cross-site scripting (XSS) in MC4WP (4.8.6 and older)

Affected: 4.8.6 and older
Fixed in: 4.8.7 *
Access needed (per CVSS): Needs an admin-level account; someone on the site has to click a link or open a page
Range from: CVE record (the advisory publisher) · score by NVD

Details from the advisory

Authenticated (admin or higher user role) Stored Cross-Site Scripting (XSS) vulnerability in ibericode's MC4WP plugin <= 4.8.6 at WordPress.

NVD CVE-2021-36833 Patchstack advisory wordpress.org

medium 6.1 CVE-2017-18577 · published 2019-08-22

Cross-site scripting (XSS) in MC4WP (older than 4.1.8)

Affected: older than 4.1.8
Fixed in: 4.1.8
Access needed (per CVSS): No login needed; someone on the site has to click a link or open a page
Range from: advisory text · score by NVD

Details from the advisory

The mailchimp-for-wp plugin before 4.1.8 for WordPress has XSS via the return value of add_query_arg.

NVD CVE-2017-18577 wordpress.org

medium 6.1 CVE-2016-10871 · published 2019-08-13

Cross-site scripting (XSS) in MC4WP (older than 4.0.11)

Affected: older than 4.0.11
Fixed in: 4.0.11
Access needed (per CVSS): No login needed; someone on the site has to click a link or open a page
Range from: advisory text · score by NVD

Details from the advisory

The mailchimp-for-wp plugin before 4.0.11 for WordPress has XSS on the integration settings page.

NVD CVE-2016-10871 wordpress.org

Recent activity

2026-09-16 — latest release on wordpress.org (4.14.1).
2026-09-19 — Reflected cross-site scripting (XSS) disclosed (CVE-2026-87917), fixed in 4.14.1.
2026-08-22 — Stored cross-site scripting (XSS) disclosed (CVE-2026-4561), fixed in 4.12.1.
2026-03-11 — Missing authorization check disclosed (CVE-2026-1781), fixed in 4.12.0.

Free. We check the CVE feeds every day and email you only when a new issue for MC4WP (mailchimp-for-wp) is published or a fix ships. Unsubscribe in one click.

Where this data comes from

Version, last update, installs: wordpress.org/plugins/mailchimp-for-wp (Plugins API), fetched 2026-11-01.
Vulnerabilities: NIST National Vulnerability Database (NVD), checked 2026-11-01. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Each record links to its CVE page and to the original advisory (Wordfence, Patchstack or WPScan) where there is one. We only list a CVE here when its references or its advisory name this exact plugin, so a few real issues may be missing; none should be about a different plugin. Spot an error? Email Daniel.

Badge for your site or docs (states facts with a date, not a verdict):

<a href="https://laskyr.com/plugins/mailchimp-for-wp"><img src="https://laskyr.com/plugins/mailchimp-for-wp/badge.svg" alt="MC4WP vulnerability status"></a>

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Is MC4WP safe? Known vulnerabilities and latest version

No known unpatched vulnerabilities in the latest version (4.14.1)

What to do

Check your version

Known vulnerabilities

Reflected cross-site scripting (XSS) in MC4WP (4.14.0 and older)

Stored cross-site scripting (XSS) in MC4WP (4.12.0 and older)

Missing authorization check in MC4WP (4.11.1 and older)

Stored cross-site scripting (XSS) in MC4WP (4.9.16 and older)

Reflected cross-site scripting (XSS) in MC4WP (4.9.9 to 4.9.16)

Missing authorization check in MC4WP (4.9.9 and older)

Stored cross-site scripting (XSS) in MC4WP (4.8.6 and older)

Cross-site scripting (XSS) in MC4WP (older than 4.1.8)

Cross-site scripting (XSS) in MC4WP (older than 4.0.11)

Recent activity

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Where this data comes from