{"schema":"threatline.record/2","record":{"id":"CVE-2026-55107","aliases":["GHSA-7pwq-q9jf-539h"],"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.","categories":["Libraries & packages"],"product":"kobako","vendor":"elct9620","ecosystem":"RubyGems","affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-55107","source_modified_at":"2026-09-30T19:49:04.193Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"kobako","vendor":"elct9620","versions":[{"status":"affected","version":">= 0.1.0, < 0.9.1"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-7pwq-q9jf-539h","source_modified_at":"2026-08-18T20:26:08.539217Z","fetched_at":"2026-10-23T18:55:00.935475Z","package":{"name":"kobako","ecosystem":"RubyGems","purl":"pkg:gem/kobako"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"fixed":"0.9.1"}]}],"versions":["0.1.0","0.1.1","0.1.2","0.2.0","0.2.1","0.3.0","0.4.0","0.5.0","0.6.0","0.6.1","0.6.2","0.7.0","0.8.0","0.9.0"]}],"fixed_versions":[{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-7pwq-q9jf-539h","source_modified_at":"2026-08-18T20:26:08.539217Z","fetched_at":"2026-10-23T18:55:00.935475Z","package":{"name":"kobako","ecosystem":"RubyGems","purl":"pkg:gem/kobako"},"version":"0.9.1"}],"cvss":10,"severity":"Critical","kev":{"listed":false},"epss":{"probability":0.00799,"percentile":0.56121,"score_date":"2026-10-23"},"published_at":"2026-09-30T17:06:00.286Z","modified_at":"2026-09-30T19:49:04.193Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-55107","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-30T19:49:04.193Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-7pwq-q9jf-539h","fetched_at":"2026-10-23T18:55:00.935475Z","source_modified_at":"2026-08-18T20:26:08.539217Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-55107","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h","tags":["exploit"]},{"source":"CVE List","url":"https://github.com/elct9620/kobako/commit/64f84700c81f44902bed9211318d5362f44987b3","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/elct9620/kobako/releases/tag/v0.9.1","tags":["x_refsource_MISC"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"poc","automatable":"yes","technical_impact":"total","assessed_at":"2026-09-30T19:48:55.982496Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-09-30T19:49:04.193Z","content_hash":"c0fd1c5c365db03fffa57382738afd74b52810d96a8907687439e6cfc8272b95"}}