CVE-2026-55107
CRITICAL
CVSS 10.0
Published: 2026-09-30
Modified: 2026-09-30
Tenable Plugin
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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.
Quick Facts
| CVE ID | CVE-2026-55107 |
| CVSS Score | 10.0 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| Published | 2026-09-30 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |