CVE-2026-87917 dvankooten CVE debrief

Who should care

Defenders responsible for WordPress installations using the MC4WP: Mailchimp for WordPress plugin should assess exposure and prioritize verification and remediation efforts. This includes reviewing the presence of this vulnerability in their environments, particularly for unauthenticated users who can be tricked into clicking on malicious links, and planning vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Why it matters

The CVE-2026-87917 vulnerability in the MC4WP: Mailchimp for WordPress plugin allows unauthenticated attackers to inject arbitrary web scripts, potentially leading to Cross-Site Scripting attacks. Defenders should prioritize verifying the presence of this vulnerability in their WordPress installations and assess exposure, particularly for unauthenticated users who can be tricked into clicking on malicious links.

• Unauthenticated attackers can inject arbitrary web scripts
• Successful exploitation requires tricking a user into clicking on a link
• Verify the presence of this vulnerability in WordPress installations
• Assess exposure, particularly for unauthenticated users

Technical summary

The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via 'data' Dynamic Content Tag in all versions up to, and including, 4.14.0 due to insufficient input sanitization and output escaping. This vulnerability allows unauthenticated attackers to inject arbitrary web scripts, potentially leading to Cross-Site Scripting attacks. Defenders should prioritize verifying the presence of this vulnerability in their WordPress installations and assess exposure, particularly for unauthenticated users who can be tricked into clicking on malicious links.

Defensive priority

Defenders should prioritize verifying the presence of this vulnerability in their WordPress installations and assess exposure, particularly for unauthenticated users who can be tricked into clicking on malicious links.

Recommended defensive actions

• Verify the presence of this vulnerability in WordPress installations
• Assess exposure, particularly for unauthenticated users
• Apply patches or updates to vulnerable versions
• Monitor for potential exploitation attempts
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its CVSS score of 6.1 and MEDIUM severity. The vulnerability is caused by insufficient input sanitization and output escaping in the 'data' Dynamic Content Tag of the MC4WP: Mailchimp for WordPress plugin.

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.