Capstone is a disassembly framework. Versions prior to 6.0.0-Alpha8 and 5.0.8 have a NULL pointer dereference in modRMRequired() and decode() when disassembling 3DNow! opcodes (0F 0F) in builds compiled with -DCAPSTONE_X86_REDUCE, allowing a remote attacker to crash any application using the reduced X86 Capstone library by supplying a crafted input containing the 4-byte sequence 0F 0F <modrm> <imm8>. Versions 6.0.0-Alpha8 and 5.0.8 patch the issue.