Flowise vulnerable to RCE via Dynamic function constructor injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2025-55346: 22.54% estimated exploitation activity in the next 30 days; percentile 97.72 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary User-controlled input flows to an unsafe implementaion of a dynamic Function constructor , allowing a malicious actor to run JS code in the context of the host (not sandboxed) leading to RCE. Details When creating a new Custom MCP Chatflow in the platform, the MCP Server Config displays a placeholder hinting at an example of the expected input structure: Behind the scene, a POST request to /api/v1/node-load-method/customMCP is sent with the provided MCP Server Config, with additional parameters (excluded for brevity): Sending the same request with the parameter mcpServerConfig equals to a plain value and not an object, for example: We enter an interesting code flow that leads to a function named convertValidJSONString (Line 103): https://github.com/FlowiseAI/Flowise/blob/416e57380ea7ce2e66f89aded61b249ff3eef3b2/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L103 Here, the value of inputString originating from mcpServerConfig is being concatenated to a dynamic…

Published by the source

6 Oct 2025, 14:08 UTC

Last modified by the source

6 Oct 2025, 14:57 UTC

Source last checked

26 Oct 2026, 12:38 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-hmgh-466j-fx4c

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-hmgh-466j-fx4c

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2025-55346

Advisory: Flowise vulnerable to RCE via Dynamic function constructor injection
IDs: CVE-2025-55346, GHSA-hmgh-466j-fx4c
Record: https://patchnext.com/advisories/cve-2025-55346 (revision 2, source checked 26 Oct 2026, 12:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm flowise: affected <= 2.2.7-patch.1

## Suggested inspection (read-only)
- `npm ls flowise --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on flowise.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-hmgh-466j-fx4c (OSV record GHSA-hmgh-466j-fx4c lists affected ranges: npm flowise >=0 <=2.2.7-patch.1)
- Verified: https://github.com/advisories/GHSA-hmgh-466j-fx4c (GitHub-reviewed advisory GHSA-hmgh-466j-fx4c lists affected ranges: npm flowise >=0 <=2.2.7-patch.1)

Commands are suggestions: review each one before running it.