WordPress Site Offline Plugin <= 1.5.6 is vulnerable to Cross Site Scripting (XSS)

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Chandra Shekhar Sahu Site Offline Or Coming Soon Or Maintenance Mode allows Stored XSS.This issue affects Site Offline Or Coming Soon Or Maintenance Mode: from n/a through 1.5.6.

Site Offline < 1.5.3 - Access Bypass

The Site Offline Or Coming Soon Or Maintenance Mode WordPress plugin before 1.5.3 prevents users from accessing a website but does not do so if the URL contained certain keywords. Adding those keywords to the URL's query string would bypass the plugin's main feature.

The site-offline plugin before 1.4.4 for WordPress lacks certain wp_create_nonce and wp_verify_nonce calls, aka CSRF.