Flowise - RCE (CVE-2025-8943)
Description
The Custom MCPs feature is designed to execute OS commands, for instance, using tools like npx to spin up local MCP Servers. However, Flowise's inherent authentication and authorization model is minimal and lacks role-based access controls (RBAC). Furthermore, in Flowise versions before 3.0.1 the default installation operates without authentication unless explicitly configured. This combination allows unauthenticated network attackers to execute unsandboxed OS commands.
psychologyCrowdSec Analysis
CVE-2025-8943 is a critical vulnerability in Flowise versions prior to 3.0.1, where the lack of default authentication and absence of role-based access controls allow unauthenticated attackers to execute arbitrary OS commands remotely. This flaw exposes affected systems to severe risks, including remote code execution, data theft, and full system compromise.
CrowdSec has been tracking this vulnerability and its exploits since 19th of November 2025.
CrowdSec network data shows that most actors exploiting CVE-2025-8943 rely on broad, untargeted scans with minimal filtering. The activity is largely automated and opportunistic in nature. CrowdSec data also reveals a clear uptick in attacks involving CVE-2025-8943 over the past week. Activity is above the usual baseline, suggesting growing attention from attackers. This may reflect rising awareness, recent exploit releases, or expanded targeting efforts.
Attackers exploit the /api/v1/node-load-method/customMCP endpoint by sending crafted JSON payloads to execute arbitrary OS commands, leveraging weak or absent authentication in vulnerable Flowise installations.
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| Event | Date |
|---|---|
| CVE Published | 2025-08-14 |
| Rule Released | 2025-11-19 |
| CrowdSec First Seen | 2025-11-27 |
Related Weaknesses
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.