What is CVE-2026-118166?

CVE-2026-118166 is a medium-severity vulnerability in Mc4wp: Mailchimp For WordPress, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 4.8/10. Published 2026-11-06.

How severe is CVE-2026-118166?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Vulnerability in Mc4wp: Mailchimp For WordPress

CVE-2026-118166

The MC4WP: Mailchimp for WordPress WordPress plugin before 4.15.0 does not prevent request-derived values in its dynamic content tags from being processed as shortcodes when a form is embedded with its block, allowing unauthenticated visitors to execute arbitrary registered shortcodes with attacker-chosen attributes. This requires the site owner to have added a request-derived tag to the form content and to embed the form with the block rather than the classic shortcode.

Published 2026-11-06 · last modified 2026-11-06.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Mc4wp: Mailchimp For WordPress

Weakness classification (CWE)

CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection)

References

wpscan.com/vulnerability/a8b2a564-25ae-4ed8-9c2c-989b104ba4c8/ (technical-description, exploit, vdb-entry)

Frequently asked questions

What is CVE-2026-118166?: CVE-2026-118166 is a medium-severity vulnerability in Mc4wp: Mailchimp For WordPress, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 4.8/10. Published 2026-11-06.
How severe is CVE-2026-118166?: Medium severity. CVSS v3 base score is 4.8 out of 10.