HTML5's cross-window messaging adds the ability to send messages directly from one window (or iframe) to another, without having to go through a server. This makes it easier to write interesting and responsive web sites, but adds vulnerability as well, since the same-origin policy does not apply here. For that reason, cross-window messaging listeners should always check message origins and use only those from trusted sites.
This rule raises an issue on each cross-window messaging listener that does not check message origins.
* https://dl.packetstormsecurity.net/papers/attack/HTML5AttackVectors_RafayBaloch_UPDATED.pdf[Packet Storm Security] - HTML 5 Modern Day Attack And Defence Vectors