{"id":"CVE-2026-55107","summary":"Kobako Vulnerable to Sandbox Escape: guest eval reaches host RCE via method_missing → public_send (any bound Service)","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.","aliases":["GHSA-7pwq-q9jf-539h"],"modified":"2026-10-02T03:47:29.120119305Z","published":"2026-09-30T17:06:00.286Z","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"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/elct9620/kobako","events":[{"introduced":"631ddc7f04bf34b39e5eb66520e1692240f8f231"},{"fixed":"98e854d2cff111bd7a8c7760d95b6f4cad6c4af8"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0.1.0"},{"fixed":"0.9.1"}]}}],"versions":["v0.9.0","kobako-rs-v0.4.0","kobako-regexp-v0.4.0","kobako-io-v0.4.0","kobako-core-v0.4.0","kobako-rs-v0.3.0","kobako-io-v0.3.0","kobako-core-v0.3.0","v0.8.0","kobako-core-v0.2.0","v0.7.0","v0.6.2","v0.6.1","v0.6.0","v0.5.0","v0.4.0","v0.3.0","v0.2.1","v0.2.0","v0.1.2","v0.1.1","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55107.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"}]}