There has been a long standing issue with Firefox not loading font from different origin than the current webpage. Usually, the issue arise when the fonts are served on CDNs.
Various solutions has been raised in other questions:
CSS @font-face not working with Firefox, but working with Chrome and IECSS @font-face not working with Firefox, but working with Chrome and IE
With the introduction of Amazon S3 CORS, is there a solution using CORS to address the font loading issue in Firefox?
edit: It would be great to see a sample of the S3 CORS configuration.
edit2: I have found a working solution without actually understanding what it did. If anyone could provide more detailed explanations about the configs and the background magic that happens on Amazon's interpretation of the config, it will be greatly appreciated, as with nzifnab who put up a bounty for it.