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FlowiseApplication · Flowiseai

CVE-2025-59528

CRITICAL · 10.0 CVSS v3.1 Published 2025-09-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Flowise is a drag & drop user interface to build a customized large language model flow. In version 3.0.5, Flowise is vulnerable to remote code execution. The CustomMCP node allows users to input configuration settings for connecting to an external MCP server. This node parses the user-provided mcpServerConfig string to build the MCP server configuration. However, during this process, it executes JavaScript code without any security validation. Specifically, inside the convertToValidJSONString function, user input is directly passed to the Function() constructor, which evaluates and executes the input as JavaScript code. Since this runs with full Node.js runtime privileges, it can access dangerous modules such as child_process and fs. This issue has been patched in version 3.0.6.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The CustomMCP node in Flowise 3.0.5 contains an RCE vulnerability where user-supplied mcpServerConfig input is passed directly to JavaScript's Function() constructor within the convertToValidJSONString function. This evaluates the input as executable code with full Node.js runtime privileges, allowing access to dangerous modules like child_process and fs for arbitrary command execution.

MitigationUpgrade to Flowise version 3.0.6 or later. Until patched, restrict or disable the CustomMCP node to prevent unauthenticated users from supplying malicious configuration.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FlowiseApplication
Affected:= 3.0.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Flowise version
    Run 'flowise --version' from the command line, or inspect the package.json file in the Flowise installation directory for the version field.
    Affected if The version is exactly 3.0.5.
  2. Locate the CustomMCP node definition
    Search the Flowise installation for files containing 'CustomMCP' or 'customMCP', typically in the nodes directory under packages/flowscribe/src/nodes/mcp or similar paths.
    Affected if The CustomMCP node file exists in the installation.
  3. Check for flows using the CustomMCP node
    Examine Flowise's internal database or flows storage (JSON files in the flows data directory) for any saved flows that include the CustomMCP node.
    Affected if Any flow contains the CustomMCP node configuration.
  4. Inspect CustomMCP node configurations for mcpServerConfig
    If CustomMCP flows exist, examine their configuration data for the 'mcpServerConfig' field which contains the user-supplied input.
    Affected if The mcpServerConfig field is present in any CustomMCP configuration.

A user is affected if Flowise version 3.0.5 is running and any flow has the CustomMCP node enabled with an mcpServerConfig input present.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Flowise version 3.0.6 or later. Until patched, restrict or disable the CustomMCP node to prevent unauthenticated users from supplying malicious configuration.

Recommended fix High confidence

3.0.6

  1. Stop the Flowise service running version 3.0.5
  2. If using npm/node: Run 'npm install [email protected]' or update package.json to version 3.0.6 and run 'npm install'
  3. If using Docker: Update your Docker image tag to 3.0.6 (e.g., 'docker pull flowiseai/flowise:3.0.6') and recreate the container
  4. Verify the upgrade was successful by checking the Flowise version at /api/v1/health or the UI
  5. Restart the Flowise service

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Flowise Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA3.0 h
13.0 hours of engineering $2,260
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-59528 in production — separate from our analysis above.

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