Mozilla has released a preview build of Firefox that includes its new Content Security Policy specification. The CSP specification is Mozilla s effort to provide Web site operators with a simpler way to protect their sites against cross-site scripting attacks and other related attacks. CSP gives site administrators the ability to specify how certain types of content interact with each other on the site, thereby providing a more granular way of defending against some common attacks. Most notably, HTTP redirects are not yet handled by CSP (but will be soon).
Source: https://threatpost.com/mozilla-releases-preview-builds-firefox-content-security-policy-100109/72258/