The Freemius SDK, as used by hundreds of WordPress plugin and theme developers, was vulnerable to Cross-Site Request Forgery and Information disclosure due to missing capability checks and nonce protection on the _get_debug_log, _get_db_option, and the _set_db_option functions in versions up to, and including 2.4.2. Any WordPress plugin or theme running a version of Freemius less than 2.4.3 is vulnerable.

The WP Secure Maintenance WordPress plugin before 1.7 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)

The WP Maintenance plugin for WordPress is vulnerable to IP Address Spoofing in all versions up to, and including, 6.1.9.2 due to insufficient IP address validation and use of user-supplied HTTP headers as a primary method for IP retrieval. This makes it possible for unauthenticated attackers to bypass maintenance mode.

Authentication Bypass by Spoofing vulnerability in WP Maintenance allows Accessing Functionality Not Properly Constrained by ACLs.This issue affects WP Maintenance: from n/a through 6.1.3.

The MainWP Dashboard – WordPress Manager for Multiple Websites Maintenance plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 4.6.0.1. This is due to missing or incorrect nonce validation on the 'posting_bulk' function. This makes it possible for unauthenticated attackers to delete arbitrary posts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

The WP Maintenance plugin for WordPress is vulnerable to Information Exposure in all versions up to, and including, 6.1.6 via the REST API. This makes it possible for unauthenticated attackers to bypass the plugin's maintenance mode obtain post and page content via REST API.

Auth. (subscriber+) SQL Injection (SQLi) vulnerability in MainWP MainWP Maintenance Extension plugin <= 4.1.1 versions.

The WP Maintenance Mode & Coming Soon WordPress plugin before 2.4.5 is lacking CSRF when emptying the subscribed users list, which could allow attackers to make a logged in admin perform such action via a CSRF attack

Authenticated Stored Cross-Site Scripting (XSS) vulnerability in Florent Maillefaud's WP Maintenance plugin <= 6.0.7 at WordPress.

Authenticated (admin+) Stored Cross-Site Scripting (XSS) in WP Maintenance plugin <= 6.0.7 versions.