While there's no way to vouch for its authenticity, it's certainly interesting enough to ponder!
The Italian Twitter account @MoviesBookIT posted the following picture to it's feed earlier today:
The suit LOOKS the part and it fits the description of Corey Stoll's Yellowjacket suit that JoBlo gave back in June:
The main villain's name is Darren Cross who, in the comics, runs Cross Technological Enterprises, a competitor company for Stark Industries and Oscorp. His cousin is the villain known as Crossfire. It's unknown if this role will be played by Patrick Wilson or Corey Stoll. He will have a suit with a similar feel to Ant-man's but more miltary style, yellow and black in color, and with a tendril-looking apparatus coming off it's back (like with Agent Venom). It's to note that in the comics Cross looks more like a pink Hulk, so there may well be some merging of attributes from other characters for this role or multiple villains at that (Yellowjacket, perhaps?).Of course that description was from the earlier, Edgar Wright screenplay and Patrick Wilson has since dropped out of the film. The Yellowjacket suit in the picture certainly fits the bill, however.
While we haven't seen much out of Ant-Man yet, if this is the suit, it certainly continues to build the profile for a film that had a LOT of trouble getting out of the gate.