Vulnerability-Lookup

GHSA-42Q4-RVCW-Q7WC

Vulnerability from github – Published: 2026-09-09 12:32 – Updated: 2026-09-09 12:32

Details

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.

Severity

6.2 (Medium)


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

6.9 (Medium)


                  
                    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

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-86547"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-09T10:22:33Z",
    "severity": "MODERATE"
  },
  "details": "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.",
  "id": "GHSA-42q4-rvcw-q7wc",
  "modified": "2026-09-09T12:32:11Z",
  "published": "2026-09-09T12:32:11Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86547"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mrubyc/mrubyc/blob/4261cf5e5ae5579e3110dab98a04b91c7d919429/src/vm.c#L1534"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mrubyc/mrubyc/blob/release4.0.0/src/vm.c#L1537"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/mrubyc-through-4.0.0-null-pointer-dereference-via-op-enter"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-86547 (GCVE-0-2026-86547)

Vulnerability from cvelistv5 – Published: 2026-09-09 10:07 – Updated: 2026-09-09 12:41

Title

mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER

Summary

Severity

6.2 (Medium)


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

6.9 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-09 12:41 UTC

CWE

CWE-476 - NULL Pointer Dereference

Assigner

VulnCheck mitre root

References

3 references

URL	Tags
https://github.com/mrubyc/mrubyc/blob/release4.0.…	technical-description
https://github.com/mrubyc/mrubyc/blob/4261cf5e5ae…	technical-description
https://www.vulncheck.com/advisories/mrubyc-throu…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
mrubyc	mrubyc	Affected: 2.0 , ≤ 4.0.0 (custom)

Date Public

2026-09-07 00:00

Credits

Harsh Raj Singhania

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-86547",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-09T12:41:01.119978Z",
                "version": "2.0.3"
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          "defaultStatus": "unaffected",
          "packageName": "mrubyc",
          "packageURL": "pkg:github/mrubyc/mrubyc",
          "product": "mrubyc",
          "repo": "https://github.com/mrubyc/mrubyc",
          "vendor": "mrubyc",
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            }
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      ],
      "credits": [
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        },
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          "name": "VulnCheck Advisory: mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER",
          "tags": [
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          "url": "https://www.vulncheck.com/advisories/mrubyc-through-4.0.0-null-pointer-dereference-via-op-enter"
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  "cveMetadata": {
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    "dateReserved": "2026-09-08T00:49:47.457Z",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-42Q4-RVCW-Q7WC

CVE-2026-86547 (GCVE-0-2026-86547)

Tags

Sightings

Nomenclature