An issue was discovered in Foxit Reader before 10.1.1 (and before 4.1.1 on macOS) and PhantomPDF before 9.7.5 and 10.x before 10.1.1 (and before 4.1.1 on macOS). An attacker can spoof a certified PDF document via an Evil Annotation Attack because the products fail to consider a null value for a Subtype entry of the Annotation dictionary, in an incremental update.