CVE-2026-86547

Description

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.

References

• https://github.com/mrubyc/mrubyc/blob/4261cf5e5ae5579e3110dab98a04b91c7d919429/src/vm.c#L1534
• https://github.com/mrubyc/mrubyc/blob/release4.0.0/src/vm.c#L1537
• https://www.vulncheck.com/advisories/mrubyc-through-4.0.0-null-pointer-dereference-via-op-enter