Overview
The Common Vulnerabilities and Exposures (CVE) system has recently identified a significant vulnerability, CVE-2025-8943, within Flowise’s Custom MCPs feature. This vulnerability, which affects versions of Flowise prior to 3.0.1, carries high potential for system compromise or data leakage. The lack of robust authentication and authorization in Flowise, compounded by the ability for unauthenticated network attackers to execute OS commands, creates a high-risk environment for any organization using these versions of the software.
Vulnerability Summary
CVE ID: CVE-2025-8943
Severity: Critical (9.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise or data leakage
Affected Products
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Product | Affected Versions
Flowise | Before 3.0.1
How the Exploit Works
The CVE-2025-8943 vulnerability exploits the Custom MCPs feature in Flowise, which is designed to execute OS commands using tools like `npx` to spin up local MCP servers. The issue lies in the lack of robust authentication and authorization mechanisms, allowing unauthenticated network attackers to execute these commands, potentially leading to unsanctioned access to the system. Further, unless explicitly configured, Flowise operates without authentication, making it even more susceptible to this vulnerability.
Conceptual Example Code
The following conceptual example demonstrates how the vulnerability might be exploited:
$ npx mcps --server https://target.example.com --execute "cat /etc/passwd"In this example, an attacker uses the `npx` tool to spin up a local MCP server targeting the vulnerable application and executes the `cat /etc/passwd` command. This action could potentially reveal sensitive system information, leading to further compromise.
Mitigation and Prevention
Users of affected versions of Flowise are strongly advised to apply the vendor patch that addresses this vulnerability. Until the patch can be applied, users may employ a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as temporary mitigation methods. These systems can monitor and block suspicious activities based on predefined or dynamically learned rules. However, these are not foolproof solutions and do not substitute the urgent need for applying the patch.
Cybersecurity is a shared responsibility. Stay vigilant, keep your software up to date, and always follow best practices to keep your systems secure.