# CVE-2026-6599: langflow-ai langflow Model Context Protocol Configuration API mcp_projects.py install_mcp_config injection

> Remote attackers can inject code via the X-Forwarded-For header in the MCP Configuration API, potentially executing arbitrary commands.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 Apr 2026
- **Updated:** 20 Apr 2026
- **Also known as:** GHSA-v66p-f7x3-4794, PYSEC-2026-2569

## What is CVE-2026-6599?

CVE-2026-6599 is a medium-severity code injection vulnerability in langflow-ai langflow, published on 20 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was detected in langflow-ai langflow up to 1.8.3. The impacted element is the function get_client_ip/install_mcp_config of the file src/backend/base/langflow/api/v1/mcp_projects.py of the component Model Context Protocol Configuration API. Performing a manipulation of the argument X-Forwarded-For results in injection. The attack may be initiated remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-707 (Improper Neutralization)

## Which versions are affected by CVE-2026-6599?

3 open source packages ship an affected version, including langflow.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `langflow` | PyPI | All versions to 1.8.3 | None |
| `langflow` | PyPI | All versions to 1.8.3 | None |
| `langflow` | PyPI | All versions to 1.8.3 | None |

## How do I fix CVE-2026-6599?

No fix has been published for CVE-2026-6599 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-6599 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6599 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6599 and fix it if it is affected.

What it is: CVE-2026-6599 is a medium-severity code injection vulnerability in langflow-ai langflow, published on 20 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6599 exists.

Affected packages and fixed versions:
- langflow (PyPI): affected all versions up to 1.8.3; no fix listed
- langflow (PyPI): affected all versions up to 1.8.3; no fix listed
- langflow (PyPI): affected all versions up to 1.8.3; no fix listed

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-2026-6599/ (Markdown: https://insights.sbomify.com/CVE-2026-6599/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6599
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6599
- OSV: https://osv.dev/vulnerability/CVE-2026-6599

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6599/
Summaries are generated and may contain mistakes; the official description above is the record.