CVE-2026-86547
mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER
- Published
- Sep 9, 2026
- Updated
- Sep 9, 2026
- Assigning CNA
- VulnCheck
- Evidence observed
- Sep 12, 2026
Primary CVSS
nvd · CVSS 4.0
CVSS: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:XLow · next 30 days
- Percentile
- 2.9%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
1Standalone proof of concept for CVE-2026-86547, a NULL pointer dereference in mrubyc op_enter() through 4.0.0.
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