The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applicationsUpgrade to the latest version of hapi.js
This description taken from the pull request provided by Patrick Kettner.
tl:dr - someone created a alphanum only swf converter, which means that they can in theory use it as a callback at a JSONP endpoint, and as a result, send data across domains.
Prepending callbacks with an empty inline comment breaks the flash parser, and prevents the issue. This is a fairly common solution currently being implemented by Google, Facebook, and GitHub.
Source: Node Security Project