Substack Mcp Plus MCP Server
substack-mcp-plus
npm
v1.0.4
Published by ty13r — no publish provenance, so origin is unverified, but the source is public: the repository link below is self-declared yet readable, so you can inspect the code before adopting it.
Unofficial Substack MCP server. Born from frustration, built with AI. 12 tools, browser auth, rich text support. Not affiliated with Substack Inc.
The grade answers one question — how safe is this server for you to adopt — so it is computed in two auditable stages. Nothing below is an opinion or an LLM's guess; every line is a real term the deterministic engine applied, and the same input always yields the same number.
1. Threat score — 100 − 7.5 = 93. What the published surface and source actually contain:
| Points | What was found | Category |
|---|---|---|
| −6.3 | Untrusted input concatenated into a command sink MTC-SRC-009 | injection |
| −1.2 | Package runs install-time scripts MTC-SUP-010 | supply-chain |
2. Client adoption risk — 93 − 7 = 86. Three small, subtract-only factors that reflect your risk in adopting it — a clean scan proves less on a powerful, unverified or barely-inspectable package, so the grade says so plainly:
| Points | Adoption-risk factor |
|---|---|
| −6 | capability blast radius (high) — client exposure if the model is manipulated |
| −1 | publisher verification (public source) — no provenance, but the source is public and inspectable |
Capability observations and info notes are shown under Findings but never scored.
Open any row's finding below for the file, line and evidence behind a deduction.
Findings 6
high Shell/command execution in server code (setup_auth.py)MTC-SRC-002
In the server's implementation (`setup_auth.py:310`): 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: port subprocess subprocess.run([sys.executable, "-m", "playwright", "install", "chromium"], check=False)
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 setup_auth.py
high Shell/command execution in server code (src/index.js)MTC-SRC-002
In the server's implementation (`src/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/index.js
medium Untrusted input concatenated into a command sink (src/index.js)MTC-SRC-009
In the server's implementation (`src/index.js:31`): 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: n const version = execSync(`${cmd} --version 2>&1`, { encoding: 'utf8' }).trim(); const match = version.matc
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
low Shell/command execution in packaging/dev tooling (scripts/postinstall.js)MTC-SRC-002
In a packaging/dev/install script (shipped, but not the server runtime) (`scripts/postinstall.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: port { execSync } 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 scripts/postinstall.js
low Shell/command execution in packaging/dev tooling (src/setup.js)MTC-SRC-002
In a packaging/dev/install script (shipped, but not the server runtime) (`src/setup.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'; 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 src/setup.js
low Package runs install-time scripts (postinstall)MTC-SUP-010
"substack-mcp-plus" executes postinstall script(s) at install time. An install hook runs at install time; most are routine build/setup, but review what it does before trusting it.
Evidence: node scripts/postinstall.js
Fix: Review the scripts; install with --ignore-scripts where possible and vet what they do.
Location: package substack-mcp-plus
Tools 12
Each tool and what it can reach — statically extracted from the published source.
create_formatted_postno sensitive capabilitydelete_draftno sensitive capabilityduplicate_postno sensitive capabilityget_post_contentno sensitive capabilityget_sectionsno sensitive capabilityget_subscriber_countno sensitive capabilitylist_draftsno sensitive capabilitylist_publishedno sensitive capabilitypreview_draftno sensitive capabilitypublish_postno sensitive capability
Show 2 more tools ↓
update_postno sensitive capabilityupload_imageno sensitive capability
What this scan could not see
- Tools were statically extracted from the published source (12 recovered), not enumerated from a running server. Tool-poisoning, Unicode-smuggling, capability and toxic-flow analysis ran on this inferred surface, but a mis-parsed registration could be missed or mis-attributed, so tool-derived findings are capped below “confirmed”. To grade the real runtime surface, scan the running server: --command "npx -y <package>".
Versions 1
Scan history per published version. The engine is deterministic — the same version always yields the same score, so a changed score means the package itself changed.
| Version | Score | Findings | Engine | Scanned |
|---|---|---|---|---|
v1.0.4 latest |
B 86/100 | 6 | 1.13.0 | 2026-09-07 |
Embed this score
Show this server's live Trust Score in your README, docs or website. The badge is served straight from the registry and updates automatically after every rescan — no API key needed. It links back to this page, so anyone who sees the grade can also read the findings behind it instead of taking a number on faith.
Verify this score yourself
The score above is reproducible: the same package version always yields the same result. Run it locally or over the free API — no account, no LLM, fully deterministic.
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