CVE-2026-86547 [MEDIUM] – mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() h

mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() handler in src/vm.c when processing untrusted bytecode. Attackers can craft malicious .mrb bytecode files with OP_ENTER instructions at the top level to crash the embedding application and cause denial of service.