secure-dev-node

A set of rules for writing safer Node.js code, the JavaScript runtime often used for servers and tools. It covers handling user input, running system commands, and storing secrets such as API keys.

In plain words
What is it for?
Use it while creating or reviewing Node.js code that handles requests, files, processes, dynamic code, environment variables, or other security-sensitive operations.
Why use it?
It reduces common security mistakes, such as letting user input control file paths or commands, executing dynamic code, or putting credentials directly in source code.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/matank001/cursor-security-rules/secure-dev-node
Clone the repo
git clone --depth 1 https://github.com/matank001/cursor-security-rules
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 564 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00564
Opus 5 $0.00000 $0.00282
Sonnet 5 $0.00000 $0.00113
Haiku 4.5 $0.00000 $0.00056

Measured yesterday against content hash 9019cc2470bb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

secure-dev-node scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

- **Rule:** Never use `req.body`, `req.query`, or similar inputs directly in `fs`, `child_process`, or system-level calls.
Origin

Copies of this mod

2 near-identical copies found in the catalogue:

secure-dev-node.mdc · 45 lines

How it starts

The opening of the file, as written. The whole thing — 45 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Secure Node.js Development

These rules apply to all Node.js code in the repository and aim to prevent common security risks through disciplined use of input validation, output encoding, and safe APIs.

All violations must include a clear explanation of which rule was triggered and why, to help developers understand and fix the issue effectively.
Generated code must not violate these rules. If a rule is violated, a comment must be added explaining the issue and suggesting a correction.

1. Do Not Use User Input in File Paths or Commands

  • Rule: Never use req.body, req.query, or similar inputs directly in fs, child_process, or system-level calls.

2. Avoid eval, Function, and vm on Dynamic Input

  • Rule: Do not use eval(), new Function(), or vm.runInNewContext() with user-controllable values.

3. Avoid Synchronous child_process and Shell Execution

  • Rule: Do not use execSync, spawnSync, or shell execution functions with untrusted input. Avoid them unless strictly necessary and audited.

4. Use Environment Variables for Secrets

  • Rule: Never hardcode secrets such as API Keys, private keys or credentials. Use environment variables and secure configuration loading.

5. Sanitize and Validate All External Input

  • Rule: All inputs (query params, request bodies, headers) must be validated and sanitized before use in logic, queries, or file access.

6. Escape Output for HTML or CLI

  • Rule: Escape dynamic output when inserting into HTML, Markdown, or command-line interfaces to prevent injection.

7. Avoid Insecure HTTP Libraries or Defaults

  • Rule: Always use HTTPS for remote calls. Do not disable SSL validation or use http in production environments.

8. Keep Dependencies Updated and Scanned

  • Rule: Regularly audit dependencies using npm audit, yarn audit, or tools like Snyk. Avoid packages that are deprecated or unmaintained.

9. Restrict Dangerous Globals and Prototypes

  • Rule: Do not modify native prototypes (e.g., Object.prototype) or rely on global mutation patterns.

Read the full file on GitHub · 45 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 45 lines · 564 tokens per session scan A 9019cc2470bb

Subscribe to this mod's changes

secure-dev-node is a cursor rule published in the GitHub repository matank001/cursor-security-rules (379 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 564 tokens. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.