Add WP Cerber to plugins with known issues

source/content/plugins-known-issues.md

@@ -11,7 +11,7 @@ cms: [wordpress]
 audience: [development]
 product: [--]
 integration: [--]
-reviewed: "2024-08-13"
+reviewed: "2024-09-06"
 ---
 
 This page lists WordPress plugins, themes, and functions that may not function as expected or are currently problematic on the Pantheon platform. This is not a comprehensive list (see [other issues](#other-issues)). We continually update it as problems are reported and/or solved. If you are aware of any modules or plugins that do not work as expected, please [contact support](/guides/support/contact-support/).
@@ -1329,6 +1329,30 @@ You will need to make this change every time the plugin is updated.
 
 ___
 
+## WP Cerber Security, Antispam & Malware Scan
+
+<ReviewDate date="2024-09-06" />
+
+WP Cerber is a premium security plugin (with a free version available) that is only available through the [WP Cerber website](https://wpcerber.com/). Previously, it was available on the WordPress plugin repository, but it was [removed](https://wordpress.org/plugins/wp-cerber/) due to a violation of the repository's guidelines.
+
+**Issue:** The WP Cerber Anti-Spam Engine makes pages uncacheable on the Pantheon Global CDN. WP Cerber creates a unique, cache-busting cookie for each visitor, which prevents users from seeing cached pages.
+
+**Solution:** Disable the Anti-Spam Engine features in the WP Cerber plugin settings.
+
+1. Navigate to the **WP Cerber** menu in the WordPress dashboard and select **Anti-Spam**.
+
+1. Disable the following options:
+   - **Protect registration form**
+   - **Protect comment form**
+   - **Protect other forms**
+
+  ![WP Cerber Anti-Spam Engine settings](../images/plugins-known-issues/wp-cerber-anti-spam-settings.png)      
+
+1. In your Pantheon dashboard, clear the cache for the environment.
+
+Your pages should now be cacheable on the Pantheon Global CDN.
+___
+
 ## WP Reset
 
 <ReviewDate date="2021-11-04" />