# CVE-2026-39417: MaxKB: RCE via MCP stdio command injection in workflow engine

> Attackers can achieve remote code execution in MaxKB by injecting commands into the MCP workflow engine via crafted JSON payloads.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 14 Apr 2026
- **Updated:** 14 Apr 2026
- **Also known as:** GHSA-pw52-326g-r5xj

## What is CVE-2026-39417?

CVE-2026-39417 is a medium-severity command injection vulnerability in 1Panel-dev MaxKB, published on 14 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain an incomplete fix for CVE-2025-53928, where a Remote Code Execution vulnerability still exists in the MCP node of the workflow engine. MaxKB only restricts the referencing code path (loading MCP config from the database). The else branch, responsible for loading mcp_servers directly from user-supplied JSON remains completely unpatched. Since mcp_source is an optional field (required=False), an attacker can simply omit it or set it to any non-referencing value to bypass the fix. By calling the workflow creation API directly with a crafted JSON payload, an attacker can inject a complete MCP node configuration with stdio transport, arbitrary command, and args — achieving RCE when the workflow is triggered via chat. This issue has been fixed in version 2.8.0.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-39417?

It affects 1 product.


Products: Maxkb Maxkb.

## How do I fix CVE-2026-39417?

No fix has been published for CVE-2026-39417 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-39417 being exploited?

There is no known exploitation of CVE-2026-39417 in the wild and no public exploit code.

## Other vulnerabilities in 1Panel-dev MaxKB

- [CVE-2025-66419](https://insights.sbomify.com/CVE-2025-66419/): MaxKB vulnerable to privilege escalation through sandbox bypass (high 8.8)
- [CVE-2025-66446](https://insights.sbomify.com/CVE-2025-66446/): MaxKB has a Python sandbox LD_PRELOAD bypass (high 8.8)
- [CVE-2025-64511](https://insights.sbomify.com/CVE-2025-64511/): MaxKB has SSRF in sandbox (high 7.4)
- [CVE-2026-39422](https://insights.sbomify.com/CVE-2026-39422/): MaxKB has Stored XSS via ChatHeadersMiddleware (medium 6.9)
- [CVE-2026-39423](https://insights.sbomify.com/CVE-2026-39423/): Stored XSS via Eval Injection in EchartsRander Component (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39417 and fix it if it is affected.

What it is: CVE-2026-39417 is a medium-severity command injection vulnerability in 1Panel-dev MaxKB, published on 14 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-39417 in the wild and no public exploit code.

Affected product: 1Panel-dev MaxKB. 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-2026-39417/ (Markdown: https://insights.sbomify.com/CVE-2026-39417/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39417
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39417
- OSV: https://osv.dev/vulnerability/CVE-2026-39417

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39417/
Summaries are generated and may contain mistakes; the official description above is the record.