CVE-2026-55107

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.

CVSS v3 10.0 CRITICAL

10.0^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 6.0

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope CHANGED

References

Link	Resource
https://github.com/elct9620/kobako/commit/64f84700c81f44902bed9211318d5362f44987b3
https://github.com/elct9620/kobako/releases/tag/v0.9.1
https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h
https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h

Configurations

No configuration.

History

30 Sep 2026, 20:17

Type	Values Removed	Values Added
References	~~() https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h -~~	() https://github.com/elct9620/kobako/security/advisories/GHSA-7pwq-q9jf-539h -

30 Sep 2026, 18:18

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-30 18:18

Updated : 2026-09-30 20:17

NVD link : CVE-2026-55107

Mitre link : CVE-2026-55107

CVE.ORG link : CVE-2026-55107

JSON object : View

Products Affected

No product.

CWE

CWE-94

Improper Control of Generation of Code ('Code Injection')

CWE-470

Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')

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