CVE-2026-5029Network attack vector

Unauthenticated code execution via exposed MCP tool

Published May 12, 2026 · Updated May 12, 2026

Missing authentication in Code Runner MCP Server all versions allows remote attackers to execute arbitrary code through its HTTP MCP endpoint. The /mcp route accepts unauthenticated run-code calls, writes supplied source to a temporary file, and passes that file to a selected interpreter through child_process.exec(). Exploitation requires the server to run with --transport http and grants the privileges of the server process to an attacker who can reach its listening port.

CVSS severityUnavailable
Unscored
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Missing authentication in Code Runner MCP Server all versions allows remote attackers to execute arbitrary code through its HTTP MCP endpoint. The /mcp route accepts unauthenticated run-code calls, writes supplied source to a temporary file, and passes that file to a selected interpreter through child_process.exec(). Exploitation requires the server to run with --transport http and grants the privileges of the server process to an attacker who can reach its listening port.

The record

CVE
CVE-2026-5029
Published
May 12, 2026
Updated
May 12, 2026
Vendor
Jun Han
Product
Code Runner MCP Server
Classifications
T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Jun Han · Code Runner MCP Serverversion=0 <=*

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo