# CVE-2026-5029: RCE in Code Runner MCP Server

> Unauthenticated attackers can execute arbitrary code via the run-code tool when the server is configured with HTTP transport.

- **Severity:** High 8.7 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 May 2026
- **Updated:** 12 May 2026
- **Also known as:** GHSA-jv4w-6p47-rhcx

## What is CVE-2026-5029?

CVE-2026-5029 is a high-severity code injection vulnerability in Code Runner MCP Server, published on 12 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A remote code execution vulnerability exists in Code Runner MCP Server when run with the --transport http option, which exposes the /mcp JSON-RPC endpoint without authentication on port 3088. An unauthenticated remote attacker can invoke the run-code MCP tool to supply arbitrary source code and execute it via child_process.exec() using the specified language interpreter. This allows execution of arbitrary code with the privileges of the user running the server. This vulnerability has not been fixed and might affect the project in all versions.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-5029?


## How do I fix CVE-2026-5029?

No fix has been published for CVE-2026-5029 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5029 being exploited?

There is no known exploitation of CVE-2026-5029 in the wild and no public exploit code.

Public exploit code:

- https://github.com/0x00phantom-hat/CVE-2026-5029-Exploit (github_poc): https://github.com/0x00phantom-hat/CVE-2026-5029-Exploit

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5029 and fix it if it is affected.

What it is: CVE-2026-5029 is a high-severity code injection vulnerability in Code Runner MCP Server, published on 12 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5029 in the wild and no public exploit code.

Affected product: Code Runner MCP Server. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5029/ (Markdown: https://insights.sbomify.com/CVE-2026-5029/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5029
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5029
- OSV: https://osv.dev/vulnerability/CVE-2026-5029

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5029/
Summaries are generated and may contain mistakes; the official description above is the record.