Medium 6.2Published Sep 9, 2026

CVE-2026-86547mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER

Updated under an hour ago (2026-10-19 08:23 UTC)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for mrubyc

Exploited in the last 30 days

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: 6.2 MEDIUM (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-476
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Sep 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

mrubyc mrubyc mrubyc:mrubyc (from the name)	from 2.0 through 4.0.0	CNA record

References

https://github.com/mrubyc/mrubyc/blob/release4.0.0/src/vm.c#L1537technical-description
https://github.com/mrubyc/mrubyc/blob/4261cf5e5ae5579e3110dab98a04b91c7d919429/src/vm.c#L1534technical-description
https://www.vulncheck.com/advisories/mrubyc-through-4.0.0-null-pointer-dereference-via-op-enterthird-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.