[Plugin: Category Icons] Conflict with WordPress Firewall 2 plugin

When WordPress Firewall 2 is installed, and the ‘Block WordPress specific terms in application parameters’ setting is enabled (which it is by default), then submitting the Category Icon form to set an icon for a specific category is blocked. WP Firewall will redirect the request to the home page, or 404 page, depending on how it’s configured.

Also, I noticed that you’re not using nonces or escaping data that’s being pulled from the database, which makes your plugin vulnerable to XSS and other attack vectors. Check out Mark Jaquith’s presentation on plugin/theme security and the Codex page on Data Validation.

https://www.ads-software.com/extend/plugins/category-icons/