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CVE-2026-86547

6.2 · MEDIUM

mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() handler in src/vm.c when processing untrusted bytecode.

Published Sep 9, 2026CWE-476EPSS 0.18%

Overview

CVE-2026-86547 is a medium-severity vulnerability. It was published on September 9, 2026 and has a CVSS 3.1 base score of 6.2 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.2, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/mrubyc/mrubyc/blob/4261cf5e5ae5579e3110dab98a04b91c7d919429/src/vm.c#L1534GitHubgithub.com/mrubyc/mrubyc/blob/release4.0.0/src/vm.c#L1537Refwww.vulncheck.com/advisories/mrubyc-through-4.0.0-null-pointer-dereference-via-op-enter

How CyberStrike helps

Frequently asked questions

What is CVE-2026-86547?

CVE-2026-86547 is a medium-severity vulnerability. It was published on September 9, 2026 and has a CVSS 3.1 base score of 6.2 (MEDIUM).

How severe is CVE-2026-86547?

This vulnerability has a CVSS 3.1 base score of 6.2, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-86547?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-86547?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-86547 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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