Overview
This blog post takes an in-depth look at the CVE-2025-59434 vulnerability, a profound flaw in the security of the drag & drop user interface, Flowise. Flowise is extensively used for building customized large language models. The vulnerability enables any user on the free tier of the Cloud-Hosted Flowise to access sensitive environment variables from other tenants, leading to a full cross-tenant data exposure. This flaw is of significant concern to organizations and individuals who utilize Flowise Cloud, as it could potentially lead to a system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-59434
Severity: Critical (9.6)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: System compromise, data leakage
Affected Products
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Product | Affected Versions
Cloud-Hosted Flowise | Prior to August 2025
How the Exploit Works
The exploit works by abusing a vulnerability in the Custom JavaScript Function node of the Cloud-Hosted Flowise. Using this node, any authenticated user on the free tier can access sensitive environment variables belonging to other tenants. This includes highly sensitive data such as OpenAI API keys, AWS credentials, Supabase tokens, and Google Cloud secrets, leading to a full cross-tenant data exposure.
Conceptual Example Code
Given the nature of this vulnerability, a malicious user might exploit it with a custom script. A simplified, conceptual example of an exploit might look like this:
// Assuming the attacker has authenticated to the service
const flowise = getAuthenticatedFlowiseInstance();
// Accessing the vulnerable function
const customJsFunction = flowise.getNode('Custom JavaScript Function');
// Attempting to access sensitive environment variables
const sensitiveData = customJsFunction.execute('process.env');
console.log(sensitiveData);In the above example, the attacker exploits the vulnerability by executing a command to access the environment variables, thereby potentially gaining access to the secrets of other tenants.
Mitigation and Recommendations
The issue has been patched in the August 2025 version of Cloud-Hosted Flowise. Users are strongly recommended to update to the latest version to mitigate this vulnerability. In cases where an immediate update is not possible, the use of a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as a temporary mitigation measure. However, these measures do not resolve the vulnerability but merely protect against it. Therefore, an update should be implemented as soon as possible to ensure data security.
