# CVE-2026-58197: ToolHive: containerized MCP servers can reach host services via host.docker.internal, enabling lateral movement

> Attackers can exploit missing network isolation and authentication in ToolHive to access host services and manipulate MCP servers.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-qg2g-g9w3-m5h8, GO-2026-6526

## What is CVE-2026-58197?

CVE-2026-58197 is a high-severity missing authorization vulnerability in stacklok toolhive, published on 18 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

ToolHive is a utility designed to simplify the deployment and management of Model Context Protocol servers. Prior to ToolHive CLI 0.30.1 and ToolHive Studio 0.38.0, locally run MCP server containers use the default network permission profile without network isolation, permitting access to host.docker.internal while ToolHive API and MCP proxy endpoints are reachable without authentication. A malicious or compromised MCP server can use the Docker gateway to contact host-local services, other ToolHive-managed MCP proxies, or the ToolHive control plane without escaping the container. This access can expose data and logs, invoke sibling MCP tools, alter process or workload state, and disrupt services. ToolHive Studio additionally sends network_isolation as false and overrides the backend's secure isolation default. This issue is fixed in ToolHive CLI 0.30.1 and ToolHive Studio 0.38.0.

Weakness: CWE-306 (Missing Authentication for Critical Functionality), CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-58197?

3 open source packages ship an affected version, including github.com/stacklok/toolhive.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/stacklok/toolhive` | Go | All versions | 0.30.1 |
| `github.com/stacklok/toolhive` | Go | All versions | 0.30.1 |
| `github.com/stacklok/toolhive` | Go | All versions | 0.30.1 |

## How do I fix CVE-2026-58197?

Upgrade github.com/stacklok/toolhive to 0.30.1 or later.

## Is CVE-2026-58197 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58197 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58197 and fix it if it is affected.

What it is: CVE-2026-58197 is a high-severity missing authorization vulnerability in stacklok toolhive, published on 18 Sep 2026. It can only be exploited from the same machine or local network, 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-2026-58197 exists.

Affected packages and fixed versions:
- github.com/stacklok/toolhive (Go): affected all versions; fixed in 0.30.1
- github.com/stacklok/toolhive (Go): affected all versions; fixed in 0.30.1
- github.com/stacklok/toolhive (Go): affected all versions; fixed in 0.30.1

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-2026-58197/ (Markdown: https://insights.sbomify.com/CVE-2026-58197/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58197
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58197
- OSV: https://osv.dev/vulnerability/CVE-2026-58197

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58197/
Summaries are generated and may contain mistakes; the official description above is the record.