According to the article, the SWF can still be executed under these circumstances, but that seems implausible to me. I would think that the browser would simply invoke the jpeg handler, fail to parse the image data, and throw an error.
I don't know if gif/jpeg rules are the same. But you can upload a GIF as a JPEG, and it will still render as a GIF, even though the file is itself JPEG. In fact, even some free image hosting sites exploit this "vulnerability". If you upload a GIF to tinypic, it will rename the file and place the
Firefox and IE seem to have no problem deciphering this so I doubt it is something that the browsers specifically disallow.
That's bullshit. It's luck. (And increasingly these days, the luck of having been born into the correct socioeconomic stratum.) The best we can do is to pursue opportunities to the utmost when they do appear and make the most of the luck we get in life.
Your statement reminded me of one of my favorite quotes.
I'm a great believer in luck, and I find the harder I work, the more I have of it. -- Thomas Jefferson
Premature optimization is the root of all evil. -- D.E. Knuth