CVE-2026-1781
MC4WP: Mailchimp for WordPress <= 4.11.1 - Missing Authorization to Unauthenticated Arbitrary Subscription Deletion
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
CISA's decision points: whether it is exploited, whether attacks can be automated, and how much control an attacker gets. Assessed (SSVC 2.0.3).What do these mean? →
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
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).
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- dvankooten MC4WP: Mailchimp for WordPress
through 4.11.1
References 7
plugins.trac.wordpress.org
- browser/mailchimp-for-wp/tags/4.11.1/includes/forms/class-form-listener.php#L53
- browser/mailchimp-for-wp/tags/4.11.1/includes/forms/class-form-listener.php#L207
- browser/mailchimp-for-wp/tags/4.11.1/includes/forms/class-form.php#L461
- changeset?sfp_email=&sfph_mail=&reponame=&new=3477825%40mailchimp-for-wp%2Ftrunk&old=3443118%40mailchimp-for-wp%2Ftrunk&sfp_email=&sfph_mail=