CVE-2026-15827
Received Received - Intake

GutenKit Blocks WordPress Plugin Mailchimp API Key Exposure

Publication date: 2026-07-23

Last updated on: 2026-07-23

Assigner: Wordfence

Description
The GutenKit Blocks plugin for WordPress is vulnerable to unauthorized access of data due to a missing capability check on the /wp-json/gutenkit/v1/mailchimp/get/lists and /wp-json/gutenkit/v1/mailchimp/get/interests REST API endpoints in versions up to, and including, 2.4.12. Both endpoints are registered with permission_callback => '__return_true', and their callbacks read the site's stored Mailchimp API key from the gutenkit_settings_list option and proxy Mailchimp audience/list, merge-field, interest-category, interest-name, and subscriber-count metadata back to the caller with no login, nonce, or capability check. This makes it possible for unauthenticated attackers to retrieve private Mailchimp audience configuration information from any site that has configured the GutenKit Mailchimp integration.

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Meta Information

Published
2026-07-23
Last Modified
2026-07-23
Generated
2026-07-23
AI Q&A
2026-07-23
EPSS Evaluated
N/A
NVD
CVE-2026-15827
EUVD
EUVD-2026-47926

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
gutenkit gutenkit_blocks to 2.4.12 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

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Executive Summary

The GutenKit Blocks plugin for WordPress has a vulnerability where two REST API endpoints expose sensitive Mailchimp configuration data without proper access controls. These endpoints allow unauthenticated users to retrieve private Mailchimp audience details, such as API keys and subscriber metadata, due to missing capability checks.

Detection Guidance

Check if the GutenKit Blocks plugin is installed and verify its version. If it is version 2.4.12 or lower, the vulnerability may be present. Use WordPress REST API endpoints /wp-json/gutenkit/v1/mailchimp/get/lists and /wp-json/gutenkit/v1/mailchimp/get/interests to test access without authentication.

Impact Analysis

If you use the GutenKit Blocks plugin with Mailchimp integration, attackers could access your Mailchimp API key and audience data without authentication. This could lead to data breaches, unauthorized access to subscriber information, or misuse of your Mailchimp account.

Compliance Impact

This vulnerability could violate GDPR by exposing personal data without consent and HIPAA if Mailchimp stores protected health information. Unauthorized access to subscriber data may lead to non-compliance with data protection regulations.

Mitigation Strategies

Update the GutenKit Blocks plugin to the latest version. If an update is not available, disable or remove the plugin immediately. Review Mailchimp API keys stored in the gutenkit_settings_list option and revoke any exposed keys.

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