The bug has apparently been lurking in the browser's UI for some time, and no known exploits apparently had occurred, but the good news is that the fix affects build 58, beta 59, and future builds.
Firefox 59 RSS
Mozilla will start to approve decentralized internet architectures for use by extensions such as DAT, IPFS, and Secure Scuttlebutt peer-to-peer protocols once Firefox 59 launches next month.
