# CVE-2026-34200: Nhost CLI MCP Server: Missing Inbound Authentication on Explicitly Bound Network Port

> Attackers can invoke privileged tools via cross-origin requests if the MCP server is explicitly bound to a network port without authentication.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 31 Mar 2026
- **Updated:** 31 Mar 2026
- **Also known as:** GHSA-6c5x-3h35-vvw2

## What is CVE-2026-34200?

CVE-2026-34200 is a high-severity missing authorization vulnerability in nhost, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Nhost is an open source Firebase alternative with GraphQL. Prior to version 1.41.0, The Nhost CLI MCP server, when explicitly configured to listen on a network port, applies no inbound authentication and does not enforce strict CORS. This allows a malicious website visited on the same machine to issue cross-origin requests to the MCP server and invoke privileged tools using the developer's locally configured credentials. This vulnerability requires two explicit, non-default configuration steps to be exploitable. The default nhost mcp start configuration is not affected. This issue has been patched in version 1.41.0.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains), CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-34200?

It affects 1 product.


Products: Nhost Cli.

## How do I fix CVE-2026-34200?

No fix has been published for CVE-2026-34200 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34200 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34200 exists.

Public exploit code:

- CVE-2026-34200 PoC (github_poc): https://github.com/skoveit/CVE-2026-34200

## Other vulnerabilities in nhost

- [CVE-2026-47671](https://insights.sbomify.com/CVE-2026-47671/): Nhost CLI local configserver allows cross-origin unauthenticated read/write access to local development configuration and secrets (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34200 and fix it if it is affected.

What it is: CVE-2026-34200 is a high-severity missing authorization vulnerability in nhost, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34200 exists.

Affected product: nhost. 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-2026-34200/ (Markdown: https://insights.sbomify.com/CVE-2026-34200/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34200
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34200
- OSV: https://osv.dev/vulnerability/CVE-2026-34200

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34200/
Summaries are generated and may contain mistakes; the official description above is the record.