Flowise has Remote Code Execution vulnerability

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

22 Sep 2025 19:54:58 UTC

Source modified

22 Sep 2025 20:24:09 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

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.

Source published

Sep 22, 2025, 7:54:58 PM (timezone not stated)

Source modified

Sep 22, 2025, 8:24:09 PM (timezone not stated)

Observed here

9 Nov 2026 03:15:25 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

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.

Source published

22 Sep 2025 20:15:39 UTC

Source modified

18 Oct 2026 21:10:00 UTC

Observed here

25 Oct 2026 03:17:27 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

## Description ### Cause of the Vulnerability The `CustomMCP` node allows users to input configuration settings for connecting to an external MCP (Model Context Protocol) 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`. ### Vulnerability Flow 1. **User Input Received**: Input is provided via the API endpoint `/api/v1/node-load-method/customMCP` through the `mcpServerConfig` parameter. 2. **Variable Substitution**: The `substituteVariablesInString` function replaces template variables like `$vars.xxx`, but no security filtering is applied during this step. 3. **Dangerous Code Execution**: The `convertToValidJSONString` function executes the input using `Function('return ' + inputString)()`. If the `inputString` contains malicious code, it gets executed in the global Node.js context, allowing actions such as command execution and file system access. ## Taint Flow - **Taint 01: Route Registration** [`index.ts` (Line 5)](https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/server/src/routes/node-load-methods/index.ts#L5) - **Taint 02: Controller** [`index.ts` (Line 57–78)](https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/server/src/controllers/nodes/index.ts#L57-L78) - **Taint 03: Service** [`index.ts` (Line 91–94)](https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/server/src/services/nodes/index.ts#L91-L94) - **Taint 04: CustomMCP Node Entry Point** [`CustomMCP.ts` (Line 132)](https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L132) - **Taint 05: Variable Substitution** [`CustomMCP.ts` (Line 220)](https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L220) - **Taint 06: Dangerous Constructor Execution** [`CustomMCP.ts` (Line 262–270)](https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L262-L270) ## Proof of Concept (PoC) ```bash curl -X POST http://localhost:3000/api/v1/node-load-method/customMCP \ -H "Content-Type: application/json" \ -H "Authorization: Bearer tmY1fIjgqZ6-nWUuZ9G7VzDtlsOiSZlDZjFSxZrDd0Q" \ -d '{ "loadMethod": "listActions", "inputs": { "mcpServerConfig": "({x:(function(){const cp = process.mainModule.require(\"child_process\");cp.execSync(\"echo !!RCE-OK!! >/tmp/RCE.txt\");return 1;})()})" } }' ``` <img width="1907" height="958" alt="image" src="https://github.com/user-attachments/assets/78b50eb1-67af-4c8b-97ea-7e2c05426962" /> When executed, this creates a file `/tmp/RCE.txt` on the server, confirming command execution. ## Impact ### Complete System Takeover and Infrastructure Threat This vulnerability allows attackers to execute arbitrary JavaScript code on the Flowise server, leading to: - Full system compromise - File system access - Command execution - Sensitive data exfiltration As only an API token is required, this poses an extreme security risk to business continuity and customer data.

Source published

15 Sep 2025 19:59:57 UTC

Source modified

13 Oct 2025 15:49:17 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Publisher rating · CRITICAL