Security advisory

{
  "id": "863f8e87fd90b8e35d40dddacab2806d0213437fcd5e3b753f53ef4dd8b6e718",
  "url": "https://osv.dev/vulnerability/CVE-2018-12248",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2018-12248",
    "summary": "An issue was discovered in mruby 1.4.1. There is a heap-based buffer over-read associated with OP_ENTER because mrbgems/mruby-fiber/src/fiber.c does not extend the stack in cases of many arguments to fiber.",
    "evidence": "osv:CVE-2018-12248",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2018-12248",
      "aliases": [
        "CVE-2018-12248"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mruby/mruby",
              "type": "GIT",
              "events": [
                {
                  "introduced": "023070a6396233974785a8fd5735b9380a884f27"
                },
                {
                  "last_affected": "023070a6396233974785a8fd5735b9380a884f27"
                },
                {
                  "fixed": "778500563a9f7ceba996937dc886bd8cde29b42b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mruby:mruby:1.4.1:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.4.1"
                      },
                      {
                        "last_affected": "1.4.1"
                      }
                    ],
                    "source": "CPE_STRING"
                  },
                  {
                    "range": [
                      {
                        "fixed": "778500563a9f7ceba996937dc886bd8cde29b42b"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.4.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-12248.json",
            "vanir_signatures": [
              {
                "id": "CVE-2018-12248-57dd5406",
                "digest": {
                  "length": 1425,
                  "function_hash": "147070256114492561439229310213750951605"
                },
                "source": "https://github.com/mruby/mruby/commit/778500563a9f7ceba996937dc886bd8cde29b42b",
                "target": {
                  "file": "mrbgems/mruby-fiber/src/fiber.c",
                  "function": "fiber_switch"
                },
                "deprecated": false,
                "signature_type": "Function",
                "signature_version": "v1"
              },
              {
                "id": "CVE-2018-12248-f67b30c9",
                "digest": {
                  "threshold": 0.9,
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                "source": "https://github.com/mruby/mruby/commit/778500563a9f7ceba996937dc886bd8cde29b42b",
                "target": {
                  "file": "mrbgems/mruby-fiber/src/fiber.c"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
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            "vanir_signatures_modified": "2026-10-20T13:26:23Z"
          }
        }
      ],
      "modified": "2026-10-20T13:26:23.741823236Z",
      "provider": "osv",
      "references": [
        "https://github.com/mruby/mruby/issues/4038",
        "https://github.com/mruby/mruby/commit/778500563a9f7ceba996937dc886bd8cde29b42b"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2018-12248",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 387683,
  "published_at": "2018-06-12T14:29:00.4+00:00"
}