mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER

{
  "id": "d80d2a39ebb697e03568c806d7a0dab46b1fb488d27478a5d1081006c40c98d9",
  "url": "https://osv.dev/vulnerability/CVE-2026-86547",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER",
    "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.",
    "evidence": "osv:CVE-2026-86547",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-86547",
      "aliases": [
        "CVE-2026-86547"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mrubyc/mrubyc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "4f904e0dea407e3cc47c29cb4bf717eecb2921c1"
                },
                {
                  "last_affected": "434bccd609f2a3e90d6bb95c458621898bc6a508"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "2.0"
                      },
                      {
                        "last_affected": "4.0.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "4.0.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "release4.0.0",
            "release3.4.1",
            "release3.4",
            "release3.3.1",
            "release3.3",
            "release3.2",
            "release3.2-rc1",
            "release3.2-beta1",
            "release3.1",
            "release2.1",
            "release2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-86547.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:33.804314069Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86547.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-86547",
        "https://www.vulncheck.com/advisories/mrubyc-through-4.0.0-null-pointer-dereference-via-op-enter",
        "https://github.com/mrubyc/mrubyc",
        "https://github.com/mrubyc/mrubyc/blob/4261cf5e5ae5579e3110dab98a04b91c7d919429/src/vm.c#L1534",
        "https://github.com/mrubyc/mrubyc/blob/release4.0.0/src/vm.c#L1537"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-476"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86547.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-86547",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 501023,
  "published_at": "2026-09-09T10:07:25.743+00:00"
}