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 `. Versions 6.0.0-Alpha8 and 5.0.8 patch the issue.