CVE-2026-4561 dvankooten CVE debrief

Who should care

WordPress site administrators and security teams should assess exposure and prioritize remediation due to the potential for authenticated attackers with Author-level access and above to inject arbitrary web scripts. This vulnerability has a medium CVSS score of 6.4, indicating a moderate severity level. Successful exploitation requires Author-level access and above, and injected scripts execute whenever a user accesses an injected page.

Why it matters

CVE-2026-4561 is a Stored Cross-Site Scripting vulnerability in the MC4WP: Mailchimp for WordPress plugin. WordPress site administrators and security teams should assess exposure and prioritize remediation.

• Authenticated attackers with Author-level access and above can inject arbitrary web scripts.
• Injected scripts execute whenever a user accesses an injected page.
• Successful exploitation requires Author-level access and above.
• Remediation priority is medium due to the CVSS score of 6.4.

Technical summary

The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the form response message post meta fields 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.

Defensive priority

Medium-priority defensive actions are recommended to address this vulnerability.

Recommended defensive actions

• Update the MC4WP: Mailchimp for WordPress plugin to a version beyond 4.12.0.
• Restrict access to the plugin's settings and form response messages.
• Monitor for suspicious activity on the WordPress site.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. The MC4WP: Mailchimp for WordPress plugin is used by numerous WordPress sites for managing Mailchimp subscriptions. The vulnerability's impact is limited to authenticated attackers with Author-level access and above. The CVE record was published on 2026-08-22T14:16:33.080Z and has not been modified since then. There are no known instances of this vulnerability being exploited in the wild.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.