{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.1.0"
              },
              {
                "fixed": "0.9.1"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "631ddc7f04bf34b39e5eb66520e1692240f8f231"
            },
            {
              "fixed": "98e854d2cff111bd7a8c7760d95b6f4cad6c4af8"
            }
          ],
          "repo": "https://github.com/elct9620/kobako",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-7pwq-q9jf-539h"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-470",
      "CWE-94"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55107.json"
  },
  "details": "Kobako is a Ruby gem that embeds a Wasm-isolated mruby interpreter inside applications, allowing execution of untrusted Ruby scripts (LLM-generated code, user formulas, student submissions, third-party plugins) in-process without giving them access to host memory, files, network, or credentials. From version 0.1.0 to before version 0.9.1, a guest mruby script running inside the Kobako sandbox can execute arbitrary Ruby in the host process, fully escaping the sandbox. This issue has been patched in version 0.9.1.",
  "id": "CVE-2026-55107",
  "modified": "2026-10-02T03:30:30.605766854Z",
  "published": "2026-09-30T17:06:00.286Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/elct9620/kobako/releases/tag/v0.9.1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55107.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55107"
    },
    {
      "type": "FIX",
      "url": "https://github.com/elct9620/kobako/commit/64f84700c81f44902bed9211318d5362f44987b3"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Kobako Vulnerable to Sandbox Escape: guest eval reaches host RCE via method_missing → public_send (any bound Service)"
}