ImageMagick before 6.9.13-57 and 7.x before 7.1.2-32 contains a type confusion flaw in the INFO, JSON and YAML encoders, where an internal method receives a pointer of an unexpected type when writing an image in a compressed format. An attacker who can cause such an image write can trigger a SIGABRT or SIGSEGV, crashing the process and causing denial of service.