CVE-2025-59528

CRITICAL

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.

CVSS v3.1 Score

10.0
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Published: 9/22/2025Modified: 9/23/2025

Related Intelligence (2)

LOWVulnerability

Max severity Flowise RCE vulnerability now exploited in attacks

Hackers are exploiting a maximum-severity vulnerability, tracked as CVE-2025-59528, in the open-source platform Flowise for building custom LLM apps and agentic systems to execute arbitrary code. [...]

CVE-2025-59528
BleepingComputer
LOWVulnerability

Flowise AI Agent Builder Under Active CVSS 10.0 RCE Exploitation; 12,000+ Instances Exposed

Threat actors are exploiting a maximum-severity security flaw in Flowise, an open-source artificial intelligence (AI) platform, according to new findings from VulnCheck. The vulnerability in question is CVE-2025-59528 (CVSS score: 10.0), a code injection vulnerability that could result in remote code execution. "The CustomMCP node allows users to input configuration settings for connecting

CVE-2025-59528
The Hacker News

References (8)

https://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L132Producthttps://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L220Producthttps://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/components/nodes/tools/MCP/CustomMCP/CustomMCP.ts#L262-L270Producthttps://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/server/src/controllers/nodes/index.ts#L57-L78Producthttps://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/server/src/routes/node-load-methods/index.ts#L5Producthttps://github.com/FlowiseAI/Flowise/blob/5930f1119c655bcf8d2200ae827a1f5b9fec81d0/packages/server/src/services/nodes/index.ts#L91-L94Producthttps://github.com/FlowiseAI/Flowise/releases/tag/flowise%403.0.6Release Noteshttps://github.com/FlowiseAI/Flowise/security/advisories/GHSA-3gcm-f6qx-ff7pExploitVendor Advisory