An unspecified vulnerability was found in Mozilla Firefox 49 and 50. It can be exploited to gain priveleges. 

Technical details

Redirection from HTTP connection to a data:URL assigns the referring of site origin to the data: URL in some cases. Because of that same-origin violations against a domain in case it loads resources from malicious sites might occur.

NB: This vulnerability have no public CVSS rating so rating can be changed by the time.

NB: At this moment Mozilla just reserved CVE numbers for this vulnerability. Information can be changed soon.

Mozilla Firefox earlier than 50.0.1

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Mozilla Foundation Security Advisory 2016-91

CVE-2016-9078