{"id":"CVE-2026-55107","published":"2026-09-30T18:18:37.550","lastModified":"2026-09-30T20:17:32.923","description":"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.","cvssScore":10,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","cwes":["CWE-94","CWE-470"],"vendors":[],"products":[],"references":[{"url":"https://github.com/elct9620/kobako/commit/64f84700c81f44902bed9211318d5362f44987b3","tags":[]},{"url":"https://github.com/elct9620/kobako/releases/tag/v0.9.1","tags":[]},{"url":"https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h","tags":[]},{"url":"https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h","tags":[]}],"exploitRefs":[{"url":"https://github.com/elct9620/kobako/commit/64f84700c81f44902bed9211318d5362f44987b3","tags":[]},{"url":"https://github.com/elct9620/kobako/releases/tag/v0.9.1","tags":[]},{"url":"https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h","tags":[]},{"url":"https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h","tags":[]}],"hasPoc":true,"ai":{"summary":"Kobako Ruby gem versions before 0.9.1 allow guest mruby scripts to escape the sandbox and execute arbitrary Ruby code in the host process, leading to remote code execution.","exploitability":"Exploitation is relatively straightforward given the preconditions of running untrusted Ruby scripts in the Kobako sandbox.","blast_radius":"If exploited, this flaw could lead to full compromise of the host system, including data theft, unauthorized code execution, and potential lateral movement.","remediation":"Upgrade to Kobako version 0.9.1 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["rce","web","ruby","sandbox-bypass"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-10-01T08:43:37.516Z"}}