Look at it this way.......

Look at it this way.... You're Microsoft, and one of your best products from yesteryear is still so popular, it's interfering with sales of newer products that you'd desperately like to move. What can you do? You've widely advertised that official support would end, and now it has, but still the users cling to their old Windows XP. What else could you do? Start a rumor that continuing to use it poses a known security risk. That ought to get some action....

But wait a minute.... the almost 28% of users still running Windows XP likely includes some of the business community that simply can't afford to play the
old 'engineered obsolescence' game with you, and their old XP does everything they need to do. Do they really need to throw it out, if this vulnerability you describe concerns the browser being used? Of course not! Just don't use that browser. Instead, use Mozilla's Firefox, or Google's Chrome, or Opera. And if you're worried about security issues, get a good third-party security program  from one of the top ten providers of those. And remember that some of the free versions these days are every bit as effective as some you must pay for.