CVE-2025-8943 in Flowise
Summary
by MITRE • 08/14/2025
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.
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Analysis
by VulDB Data Team • 08/19/2025
The vulnerability described in CVE-2025-8943 represents a critical security flaw within Flowise's Custom MCPs functionality that stems from insufficient authentication and authorization controls. This issue manifests when the system's default installation operates without mandatory authentication mechanisms, creating an environment where unauthenticated network attackers can exploit the system's command execution capabilities. The Custom MCPs feature is specifically designed to execute operating system commands through tools such as npx for launching local MCP Servers, which inherently provides powerful system-level access when properly configured. However, the absence of robust authentication controls in versions prior to 3.0.1 creates a significant attack surface where malicious actors can bypass normal access controls and directly invoke these command execution functions.
The technical implementation of this vulnerability aligns with CWE-306, which addresses missing authentication mechanisms, and CWE-78, which covers OS command injection vulnerabilities. The flaw occurs because Flowise's authentication model is minimal and lacks role-based access controls that would normally restrict command execution privileges to authorized users only. When the system operates in its default configuration without explicit authentication setup, any network attacker with access to the system can exploit the Custom MCPs feature to execute arbitrary operating system commands. This represents a severe privilege escalation vulnerability since the system's default behavior does not require authentication for command execution, allowing attackers to perform actions that could include system compromise, data exfiltration, or further network exploration.
The operational impact of this vulnerability extends beyond simple command execution, as it fundamentally undermines the security boundaries of the system. Attackers can leverage this vulnerability to perform actions such as installing malicious software, modifying system configurations, accessing sensitive data, or using the compromised system as a launch point for further attacks within the network. The lack of RBAC means that there are no granular controls to limit who can access the Custom MCPs functionality, making the entire system vulnerable to exploitation. This vulnerability is particularly dangerous because it affects the default installation configuration, meaning that systems deployed without explicit security hardening are inherently vulnerable. The attack surface is further expanded by the fact that the vulnerability can be exploited remotely without requiring any prior access credentials, making it an attractive target for automated attacks and exploitation tools.
Mitigation strategies for CVE-2025-8943 should focus on implementing proper authentication and authorization controls within Flowise. The most immediate solution involves upgrading to version 3.0.1 or later where authentication mechanisms are properly enforced. Organizations should also implement explicit authentication configuration during deployment, ensuring that access to the Custom MCPs feature requires proper credentials and role-based permissions. Network segmentation and firewall rules should be implemented to restrict access to the Flowise system to authorized networks only, while additional monitoring should be deployed to detect unauthorized command execution attempts. The implementation of these controls aligns with ATT&CK technique T1059.001 for command and scripting interpreter, which addresses the execution of malicious code through command-line interfaces. Security teams should also consider implementing principle of least privilege controls and regular security assessments to ensure that the system maintains proper access controls and that the Custom MCPs functionality is properly secured against unauthorized access attempts.