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securitycritical PriorityID: input-sanitization-sql-injection

SQL Injection Defense & Parameterized Query Standard

Eliminate SQL injection: strictly use parameterized queries or prepared statements, avoid string interpolation in SQL strings, and validate identifiers against strict whitelists.

Prohibited Anti-Pattern: AI uses template literals (f-strings / `${userInput}`) to construct dynamic SQL queries.

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---
description: SQL Injection Defense & Parameterized Query Standard - Eliminate SQL injection: strictly use parameterized queries or prepared statements, avoid string interpolation in SQL strings, and validate identifiers against strict whitelists.
globs: **/*.sql, **/db/**/*.{ts,py,go}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/input-sanitization-sql-injection"
---

# SQL Injection Defense & Parameterized Query Standard

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: AI uses template literals (f-strings / `${userInput}`) to construct dynamic SQL queries.

## System Constraints
You are a database security architect. Never concatenate or interpolate user input into SQL queries. Always use parameterized queries ($1, ? or :param). For dynamic ORDER BY columns or table names, validate against a strict hardcoded whitelist.

## Strict Guidelines
- Never use f"SELECT ... {user_input}" or `SELECT ... ${userInput}`; use parameterized placeholders.
- For dynamic column sorting (ORDER BY), match against an explicit set of allowed column identifiers.
- Sanitize HTML content with DOMPurify on client and sanitize-html on server to prevent XSS.

## Bad vs Good Implementations
### Parameterized SQL Query vs Dangerous String Interpolation

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: String interpolation allows arbitrary SQL injection, enabling data extraction or database drops.
```typescript
// CRITICAL VULNERABILITY: Raw string interpolation in SQL
export async function searchUsers(searchTerm: string) {
  // Attacker can pass: ' OR '1'='1' --
  const query = `SELECT * FROM users WHERE name LIKE '%${searchTerm}%'`;
  return pool.query(query);
}
```

#### Production Standard (Correct)
> **Standard**: Database driver treats user input strictly as literal parameter data, completely neutralizing injection.
```typescript
// Production Standard: Parameterized Query
export async function searchUsers(searchTerm: string) {
  const query = `SELECT id, name, email FROM users WHERE name ILIKE $1`;
  return pool.query(query, [`%${searchTerm}%`]);
}
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

PostgreSQL Database MCP
Verify query execution plans and parameter binding.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

SQL Query Injection Auditor
Audit raw SQL statements across repositories for unsafe string concatenation.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: SQL Injection Defense & Parameterized Query Standard

SQL Injection Defense & Parameterized Query Standard defines an industrial-grade behavioral standard for security engineering. Eliminate SQL injection: strictly use parameterized queries or prepared statements, avoid string interpolation in SQL strings, and validate identifiers against strict whitelists. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: AI uses template literals (f-strings / `${userInput}`) to construct dynamic SQL queries. Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftAI uses template literals (f-strings / `${userInput}`) to construct dynamic SQL queries.Critical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Never use f"SELECT ... {user_input}" or `SELECT ... ${userInput}`

Never use f"SELECT ... {user_input}" or `SELECT ... ${userInput}`; use parameterized placeholders.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

For dynamic column sorting (ORDER BY), match against an explicit set of allowed column identifiers.

For dynamic column sorting (ORDER BY), match against an explicit set of allowed column identifiers.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Sanitize HTML content with DOMPurify on client and sanitize-html on server to prevent XSS.

Sanitize HTML content with DOMPurify on client and sanitize-html on server to prevent XSS.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is SQL Injection Defense & Parameterized Query Standard critical for AI coding assistants?

Eliminate SQL injection: strictly use parameterized queries or prepared statements, avoid string interpolation in SQL strings, and validate identifiers against strict whitelists. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (AI uses template literals (f-strings / `${userInput}`) to construct dynamic SQL queries.) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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