CVE-2026-86547

mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER

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.

Affected

mrubyc

CVSS v4.0 VULNCHECK

6.9 MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 VULNCHECK

6.2 MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.18% chance of exploitation in the next 30 days, 7th percentile

Published

2026-09-09

Proof-of-concept exploits (1)

• HarshRajSinghania/cve-2026-86547-mrubyc-op-enter0★ · 2026-09-12

References

• CVE Record
• NVD entry

Related

• CVE-2017-0144
• CVE-2019-0703
• CVE-2020-0796
• CVE-2021-1675
• CVE-2022-38023
• CVE-2023-1545