# CVE-2026-58057: Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity

> Authenticated users can bypass environment variable denylists via case sensitivity on Windows to execute arbitrary code in the Flowise server.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **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:** 28 Jun 2026
- **Updated:** 29 Jun 2026
- **Also known as:** GHSA-rqqr-m697-6jq3

## What is CVE-2026-58057?

CVE-2026-58057 is a low-severity vulnerability in Flowiseai Flowise, published on 28 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Flowise before 3.1.3 validates Custom MCP stdio environment variables against a denylist using a case-sensitive comparison, so on Windows, where environment names are case-insensitive, supplying 'node_options' bypasses the NODE_OPTIONS denylist entry. An authenticated user who can configure a Custom MCP node can thereby inject NODE_OPTIONS --require and execute arbitrary code in the Flowise server context.

Weakness: CWE-178 (Improper Handling of Case Sensitivity)

## Which versions are affected by CVE-2026-58057?

It affects 1 product.


Products: Flowiseai Flowise.

## How do I fix CVE-2026-58057?

No fix has been published for CVE-2026-58057 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-58057 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58057 exists.

Public exploit code:

- Flowise Windows RCE exploit for CVE-2026-58057. Bypasses environment variable validation via case-sensitive flaw. Uses node_options to inject arbitrary code through MCP stdio. Supports reverse shell, persistence, file upload, credential dumping. For authorized security testing only. (github_poc): https://github.com/CerberusMrXi/Flowise-CVE-2026-58057-exploit
- Flowise  3.1.3 - arbitrary code execution (exploitdb)

## Other vulnerabilities in Flowiseai Flowise

- [CVE-2025-71338](https://insights.sbomify.com/CVE-2025-71338/): Flowise through 2.2.7 - Arbitrary File Write to Remote Code Execution via document-store API (critical 10.0)
- [CVE-2026-40933](https://insights.sbomify.com/CVE-2026-40933/): Flowise: Authenticated RCE Via MCP Adapters (critical 10.0)
- [CVE-2025-61913](https://insights.sbomify.com/CVE-2025-61913/): Flowise is vulnerable to arbitrary file read, arbitrary file write (critical 10.0)
- [CVE-2025-59528](https://insights.sbomify.com/CVE-2025-59528/): Flowise has Remote Code Execution vulnerability (critical 10.0)
- [CVE-2026-52098](https://insights.sbomify.com/CVE-2026-52098/): Code injection in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58057 and fix it if it is affected.

What it is: CVE-2026-58057 is a low-severity vulnerability in Flowiseai Flowise, published on 28 Jun 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-2026-58057 exists.

Affected product: Flowiseai Flowise. 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-2026-58057/ (Markdown: https://insights.sbomify.com/CVE-2026-58057/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58057
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58057
- OSV: https://osv.dev/vulnerability/CVE-2026-58057

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58057/
Summaries are generated and may contain mistakes; the official description above is the record.