Flow Nexus MCP Server

Tools that read sensitive data ([execution_files_list, storage_list]) and tools that can send data out ([agent_spawn, sandbox_upload, storage_upload, template_create]) are exposed together. An agent can move private data to the sink.

Evidence: sources [execution_files_list, storage_list] → sinks [agent_spawn, sandbox_upload, storage_upload, template_create]

Fix: Keep secret-reading and egress capabilities on separate, separately-approved servers.

Location: flow execution_files_list → agent_spawn

Tool "agent_spawn" appears to run shell commands or evaluate code (keyword "spawn" in tool name). Arbitrary execution driven by model input is one of the most dangerous MCP capabilities; combined with any untrusted input it becomes RCE.

Fix: Sandbox execution, allowlist commands/arguments, and never pass model output to a shell unescaped.

Location: tool agent_spawn

Tool "template_create" appears to run shell commands or evaluate code (parameter "command"). Arbitrary execution driven by model input is one of the most dangerous MCP capabilities; combined with any untrusted input it becomes RCE.

Fix: Sandbox execution, allowlist commands/arguments, and never pass model output to a shell unescaped.

Location: tool template_create

In the server's implementation (`bin/flow-nexus.js:9`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: import { spawn } from 'child_process'; import { fileURLToPath } from 'url'; import { dirname, join } from 'path'; impor

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server bin/flow-nexus.js

In the server's implementation (`bin/mcp.js:8`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: import { spawn } from 'child_process'; import { fileURLToPath } from 'url'; import { dirname, join } from 'path'; cons

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server bin/mcp.js

In the server's implementation (`cli.js:10`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: exec, spawnSync } from 'child_process'; import { promisify } from 'util'; import supabaseClient from './src/services/sup

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server cli.js

In the server's implementation (`src/cli/index.js:3`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: import { spawn } from 'child_process'; import { fileURLToPath } from 'url'; import { dirname, join } from 'path'; impor

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/cli/index.js

In the server's implementation (`src/cli/payment-cli.js:78`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: exec } = await import('child_process'); exec(`echo "${result.paymentUrl}" | pbcopy`); console.log(c

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/cli/payment-cli.js

In the server's implementation (`src/index-real.js:16`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: ; import { exec } from 'child_process'; import { promisify } from 'util'; const execAsync = promisify(exec); const requ

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/index-real.js

In the server's implementation (`src/index.js:39`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: ; import { exec } from 'child_process'; import { promisify } from 'util'; import distributedNeuralTools from './tools/di

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/index.js

In the server's implementation (`src/mcp-bridge.js:8`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: import { spawn } from 'child_process'; import http from 'http'; import { fileURLToPath } from 'url'; import { dirname,

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/mcp-bridge.js

In the server's implementation (`src/services/auth-service.js:46`): A hardcoded outbound call to a fixed external host inside server code is a classic exfiltration/telemetry channel — especially paired with reads of local data. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: const response = await fetch('https://api.flow-nexus.com/auth/validate', { method: 'POST', headers: { 'Cont

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/services/auth-service.js

In the server's implementation (`src/cli/payment-cli.js:79`): A shell/process command assembled from concatenated or interpolated values is command injection when any part is attacker-influenced — the OWASP canonical RCE flow. Verify what reaches the interpolated value. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: ld_process'); exec(`echo "${result.paymentUrl}" | pbcopy`); console.log(chalk.green('✅ Payment link

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server src/cli/payment-cli.js

Tool "template_create" takes a command-shaped parameter "claude_command_template" with no enum/pattern constraint. Free-form, model- or attacker-controlled arguments reaching a shell is the command-injection precondition.

Fix: Constrain the parameter (enum/pattern), or build the command from a fixed template with escaped args.

Location: tool template_create · inputSchema.properties.claude_command_template

Tool "template_create" takes a command-shaped parameter "startup_script" with no enum/pattern constraint. Free-form, model- or attacker-controlled arguments reaching a shell is the command-injection precondition.

Fix: Constrain the parameter (enum/pattern), or build the command from a fixed template with escaped args.

Location: tool template_create · inputSchema.properties.startup_script

In the server's implementation (`bin/flow-nexus.js:241`): Loading a module chosen at runtime (from a variable) can pull in and run attacker-influenced code paths. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: : serverPath; import(serverUrl).then(module => { const FlowNexusServer = module.FlowNexusServer || modul

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server bin/flow-nexus.js

A hardcoded JSON Web Token (a public-by-design (anon/publishable) key — RLS, not secrecy, protects it) appears in `scripts/init-user.js:28`. Verify whether this is a real credential; if so, remove and rotate it.

Evidence: JSON Web Token: eyJh…(redacted)

Fix: Remove the secret, rotate it, and load credentials from the environment or a secret store.

Location: server scripts/init-user.js

A hardcoded JSON Web Token (a public-by-design (anon/publishable) key — RLS, not secrecy, protects it) appears in `src/config/supabase-config.js:9`. Verify whether this is a real credential; if so, remove and rotate it.

Evidence: JSON Web Token: eyJh…(redacted)

Fix: Remove the secret, rotate it, and load credentials from the environment or a secret store.

Location: server src/config/supabase-config.js

A hardcoded JSON Web Token (a public-by-design (anon/publishable) key — RLS, not secrecy, protects it) appears in `src/services/supabase-client.js:26`. Verify whether this is a real credential; if so, remove and rotate it.

Evidence: JSON Web Token: eyJh…(redacted)

Fix: Remove the secret, rotate it, and load credentials from the environment or a secret store.

Location: server src/services/supabase-client.js

Tool "agent_spawn" can mutate/egress but declares no destructiveHint. Clients that don't default to spec-safe behavior may not prompt before running it.

Fix: Declare accurate annotations, and gate destructive tools on user confirmation regardless.

Location: tool agent_spawn

Tool "template_create" can mutate/egress but declares no destructiveHint. Clients that don't default to spec-safe behavior may not prompt before running it.

Fix: Declare accurate annotations, and gate destructive tools on user confirmation regardless.

Location: tool template_create

Tool "execution_files_list" takes a path parameter "file_type" with no constraint. Without a canonicalize-and-contain check (not visible statically), this permits ../ traversal outside the intended root.

Fix: Resolve and verify the path stays within an allowed root; reject traversal sequences.

Location: tool execution_files_list · inputSchema.properties.file_type

Tool "storage_list" takes a path parameter "path" with no constraint. Without a canonicalize-and-contain check (not visible statically), this permits ../ traversal outside the intended root.

Fix: Resolve and verify the path stays within an allowed root; reject traversal sequences.

Location: tool storage_list · inputSchema.properties.path

In a packaging/dev/install script (shipped, but not the server runtime) (`scripts/debug-chat.js:3`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: import { spawn } from 'child_process'; import path from 'path'; import { fileURLToPath } from 'url'; const __filename

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server scripts/debug-chat.js

In a packaging/dev/install script (shipped, but not the server runtime) (`scripts/fix-critical-issues.js:351`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.

Evidence: import { exec } from 'child_process'; import { promisify } from 'util'; import chalk from 'chalk'; const execAsync =

Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.

Location: server scripts/fix-critical-issues.js