WordPress MailChimp Plugin Unauth Stored XSS (CVE-2026-15052)

Vulnerability Overview Vulnerability Name: MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder <= 4.3.3 - Unauthenticated Stored Cross-Site Scripting via Form Field Values CVE ID: CVE-2026-15052 CVSS Score: 7.2 (High) Release Date: July 31, 2026 Last Updated: August 1, 2026 Researcher: she11f Impact Scope Software Type: Plugin Software Name: MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder Affected Versions: <= 4.3.3 Fixed Version: 4.3.4 Remediation Recommendation: Upgrade to version 4.3.4 or later patched versions. Vulnerability Details Description: The MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting (XSS). Attackers can inject arbitrary web scripts via form field values, which are executed when users visit the affected page. Vulnerability Type: Improper Neutralization of Input During Web Page Generation (Cross-site Scripting) CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N References plugins.trac.wordpress.org Additional Information Recent Related Vulnerabilities: - MailChimp Subscribe Forms <= 4.1 - Authenticated (Contributor+) Stored Cross-Site Scripting (CVE-2025-22727) - MailChimp Subscribe Forms <= 4.0.9.7 - Authenticated (Editor+) Stored Cross-Site Scripting (CVE-2024-43211) - MailChimp Subscribe Forms <= 4.0.9.1 - Authenticated (Administrator+) Stored Cross-Site Scripting (CVE-2023-33328) - MailChimp Subscribe Forms <= 4.0.9.3 - Open Redirect (CVE-2023-32517) - MailChimp Subscribe Form, Optin Builder, PopUp Builder, Form Builder < 1.2 - Remote Code Execution (CVE-2015-4421) Notes This vulnerability database is completely free to query and use, containing all vulnerability data identical to that presented in the user interface. 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Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Additional Information Wordfence Intelligence: Provides personal and commercial API access, including free Webhook integration. Additional Information Wordfence Intelligence: Completely free to access and query. Addition

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WordPress MailChimp Plugin Unauth Stored XSS (CVE-2026-15052)