The Custom MCPs feature in Flowise allows for the execution of OS commands, such as using `npx` to start local MCP Servers. However, the authentication and authorization model is minimal, lacking role-based access controls (RBAC). In versions prior to 3.0.1, the default installation operates without authentication, enabling unauthenticated attackers to execute unsandboxed OS commands.
Details
| Severity | Base Score | CVE |
|---|---|---|
| CRITICAL | 9.8 | CVE-2025-8943 |
Exploitation
To exploit this vulnerability, an attacker can send crafted requests to the Flowise application, leveraging the lack of authentication to execute arbitrary OS commands. This can lead to unauthorized access and control over the affected system.
Affected Products
- Flowise: Affected versions prior to 3.0.1 lack proper authentication, allowing command execution.
Mitigation
To mitigate this vulnerability, it is crucial to upgrade to Flowise version 3.0.1 or later, which includes necessary authentication mechanisms. Additionally, implementing role-based access controls (RBAC) can help secure the application against unauthorized command execution.