CVE-2025-59528 — flowise
CRITICALCVE-2025-59528 is a critical-severity (CVSS 10) Code Injection vulnerability in flowise. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for flowise — see the affected versions and patch details below.
Flowise has Remote Code Execution vulnerability
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-59528.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
flowisenpmDescription
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
- User Input Received: Input is provided via the API endpoint
/api/v1/node-load-method/customMCPthrough themcpServerConfigparameter. - Variable Substitution: The
substituteVariablesInStringfunction replaces template variables like$vars.xxx, but no security filtering is applied during this step. - Dangerous Code Execution: The
convertToValidJSONStringfunction executes the input usingFunction('return ' + inputString)(). If theinputStringcontains 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) -
Taint 02: Controller
index.ts(Line 57–78) -
Taint 03: Service
index.ts(Line 91–94) -
Taint 04: CustomMCP Node Entry Point
CustomMCP.ts(Line 132) -
Taint 05: Variable Substitution
CustomMCP.ts(Line 220) -
Taint 06: Dangerous Constructor Execution
CustomMCP.ts(Line 262–270)
Proof of Concept (PoC)
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;})()})"
}
}'
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | flowise | ≥ 3.0.5&&< 3.0.6 | 3.0.6npm install flowise@3.0.6 |
Affected Products
flowiseflowiseaiResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Flowise 3.0.4 - Remote Code Execution (RCE)
by nltt0 · Oct 31, 2025
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for flowise, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update flowise to 3.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59528 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
How to detect CVE-2025-59528
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2025-59528 -u https://target- Template
- Flowise - Remote Code Execution
- Severity
- critical
- Impact
- Attackers can execute arbitrary code with full Node.js privileges, potentially leading to full system compromise.
- Remediation
- Update to version 3.0.6 or later.
Template by ProjectDiscovery nuclei-templates (xtr0nix), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2025-59528 in your dependencies?
Find it across npm, including transitive dependencies.