CRITICAL

CVE-2026-55107

CVSS v3

CRITICAL

EPSS Score

0.9 %

exploit probability, as of 2026-10-01

CISA KEV

known exploited

Exploitation

—

SSVC status

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

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Published: 2026-09-30
Last Modified: 2026-09-30

Frequently asked questions

What is CVE-2026-55107?

Is CVE-2026-55107 actively exploited?

Active exploitation of CVE-2026-55107 has not been confirmed. Its EPSS score was 0.9% on 2026-10-01, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-55107?

CVE-2026-55107 has a CVSS v3 base score of 10 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

Is CVE-2026-55107 affecting your environment?

Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.

Check an IP Search CVEs SIEM & TIP integrations

No credit card required · 500 free checks/month · Free API key

Other 2026 vulnerabilities worth triaging

Ranked by exploit probability (EPSS).

Back to CVE Database