GitHub Security Advisory: GHSA-cvrr-qhgw-2mm6
Package: flowise (NPM)
Severity: HIGH (CVSS 7.7)
CWE: CWE-20: Improper Input Validation
Vulnerable versions: <= 3.0.13
Patched in: 3.1.0

Summary: Flowise: Parameter Override Bypass Remote Command Execution

Details:
### Summary

Flowise is vulnerable to a critical unauthenticated remote command execution (RCE) vulnerability. It can be exploited via a parameter override bypass using the `FILE-STORAGE::` keyword combined with a `NODE_OPTIONS` environment variable injection. This allows for the execution of arbitrary system commands with root privileges within the containerized Flowise instance, requiring only a single HTTP request and no authentication or knowledge of the instance.

### Details

The vulnerability is in a validation check within the `replaceInputsWithConfig` function within `packages/server/src/utils/index.ts`. The check for `FILE-STORAGE::` was intended to handle file-type inputs but has three issues:

1. Uses .includes() instead of .startsWith(): The check passes if FILE-STORAGE:: appears ANYWHERE in the string, not just at the beginning. A remote user can embed it in a comment: /* FILE-STORAGE:: */ { custom config }

2. No parameter type validation: The check doesn't verify that the parameter is actually a file-type input. It applies to ANY parameter name, including mcpServerConfig.

3. Complete bypass, not partial: When the check passes, it skips the isParameterEnabled() call entirely, allowing modification of parameters that administrators never authorized.

**Vulnerable Code (`FILE-STORAGE::` bypass):**
```typescript
// packages/server/src/utils/index.ts, line 1192-1198
// Skip if it is an override "files" input, such as pdfFile, txtFile, etc
if (typeof overrideConfig[config] === 'string' && overrideConfig[config].includes('FILE-STORAGE::')) {
    // pass  <-- BYPASSES ALL VALIDATION
} else if (!isParameterEnabled(flowNodeData.label, config)) {
    // Only proceed if the parameter is enabled
    continue
}
```

This bypass allows an attacker to override the `mcpServerConfig` and inject a malicious `NODE_OPTIONS` value. The `Custom MCP` node's environment variable blocklist does not include `NODE_OPTIONS`, enabling an attacker to use the `--experimental-loader` to execute arbitrary JavaScript code before the main process starts.

**Vulnerable Code (`NODE_OPTIONS` not blocked):**
```typescript
// packages/components/nodes/tools/MCP/core.ts, line 248-254
const dangerousEnvVars = ['PATH', 'LD_LIBRARY_PATH', 'DYLD_LIBRARY_PATH']

for (const [key, value] of Object.entries(env)) {
    if (dangerousEnvVars.includes(key)) {
        throw new Error(`Environment variable '${key}' modification is not allowed`)
    }
}
```

### Requirements

**API Override Enabled**
The chatflow must have "API Override" toggled ON in Chatflow Configuration.
**Public Chatflow**
The chatflow must be shared publicly.
**MCP Node**
The chatflow must contain a MCP tool node (Custom MCP tool was tested and confirmed).

Although not enabled by default, the API Override feature is a powerful and officially documented capability that may be used in production deployments. Its primary purpose is to make chatflows dynamic and user-aware.

Common use cases that necessitate enablin