NULL pointer dereference in Mrubyc

CVE-2026-86547

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.

CVSS v3 metric

CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-86547?
CVE-2026-86547 is a medium-severity vulnerability in Mrubyc, classified under NULL Pointer Dereference. CVSS score: 6.2/10. Published 2026-09-09.
How severe is CVE-2026-86547?
Medium severity. CVSS v3 base score is 6.2 out of 10.