Security.fileuri.strict origin policy
From MozillaZine Knowledge Base
When local HTML files (e.g., those located on your hard drive) are loaded into the browser, the scripts and links within have restrictions on what they can see and do. Those restrictions are determined by the same-origin policy for local files, which this preference controls.
This preference obsoletes security.fileuri.origin_policy.
Possible values and their effects
Local documents have access to other local documents in the same directory and in subdirectories, but not directory listings. (Default)
Local documents have access to all other local documents, including directory listings.
If you do development with local files and need to be able to retrieve other local files, you may need to set this preference to false. Otherwise, leaving it set to true offers the most security.
First checked in
Has an effect in