The Woody code snippets plugin for WordPress, called “Insert Header Footer Code, AdSense Ads,” has a security flaw that allows hackers to insert harmful code on web pages. This can happen when the plugin’s settings are changed by someone with administrator access. The issue affects all versions up to 2.4.10 and is caused by not properly filtering and escaping input. This vulnerability only affects websites with multiple sub-sites or those with certain security settings disabled.