Description
The MailChimp Forms by MailMunch plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `sign_in()` and `sign_up()` AJAX handlers in all versions up to, and including, 3.2.7. This makes it possible for authenticated attackers, with Subscriber-level access and above, to relink the site's MailMunch integration to an attacker-controlled MailMunch account by submitting attacker-supplied credentials. Once relinked, all subscriber data captured by the plugin's forms is delivered to the attacker, and the forms/landing pages rendered on the site are pulled from the attacker's MailMunch account.
References8
- plugins.trac.wordpress.org/browser/mailchimp-forms-by-mailmunch…
- plugins.trac.wordpress.org/browser/mailchimp-forms-by-mailmunch…
- plugins.trac.wordpress.org/browser/mailchimp-forms-by-mailmunch…
- plugins.trac.wordpress.org/browser/mailchimp-forms-by-mailmunch…
- plugins.trac.wordpress.org/browser/mailchimp-forms-by-mailmunch…
- plugins.trac.wordpress.org/browser/mailchimp-forms-by-mailmunch…
- plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&repo…
- www.wordfence.com/threat-intel/vulnerabilities/id/c9d00ee8-b9df…
Metrics
- CVSS 3.1
-
8.1
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N - EPSS — exploit probability
- 0% percentile: 43 · as of 13 November 2026
- CWE
- CWE-862
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.