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Vulnerability · Published Mar 11, 2026 · Assigned by Wordfence

CVE-2026-1781MC4WP: Mailchimp for WordPress <= 4.11.1 - Missing Authorization to Unauthenticated Arbitrary Subscription Deletion

Medium 6.5

In plain English

A medium-severity missing authorization in MC4WP: Mailchimp for WordPress from dvankooten. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.3%top 76.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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).

Affected products (as reported)

VendorProductVersions
dvankooten MC4WP: Mailchimp for WordPress 0 – through 4.11.1

Weakness: CWE-862 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References