SECURITY_IMPROVEMENTS.md

Security & Stability Improvements

This document summarizes the critical security and stability improvements made to sqlite-vec-client.

Completed Tasks

Security Enhancements

1. SQL Injection Prevention

• Table Name Validation: Added strict validation for table names using regex pattern ^[a-zA-Z_][a-zA-Z0-9_]*$
• Prevents: SQL injection attacks through malicious table names
• Implementation: validation.py::validate_table_name()

2. Input Validation

Added comprehensive validation for all user inputs:

• Dimension validation: Must be positive integer
• top_k validation: Must be positive integer
• limit validation: Must be positive integer
• offset validation: Must be non-negative integer
• List length matching: Ensures texts, embeddings, and metadata lists have matching lengths

Error Handling Improvements

1. Custom Exception Classes

Created a hierarchy of custom exceptions in exceptions.py:

• VecClientError: Base exception for all client errors
• ValidationError: Input validation failures
• TableNameError: Invalid table name errors
• TableNotFoundError: Missing table errors
• ConnectionError: Database connection failures
• DimensionMismatchError: Embedding dimension mismatches

2. Enhanced Error Messages

All exceptions now provide clear, actionable error messages:

• Explains what went wrong
• Suggests how to fix the issue
• Includes relevant context (e.g., expected vs actual values)

3. Exception Handling in Public Methods

Added try-catch blocks to all critical operations:

• create_connection(): Catches connection and extension loading errors
• similarity_search(): Catches table not found errors
• add(): Catches table not found errors
• All methods validate inputs before execution

New Files

1. sqlite_vec_client/exceptions.py: Custom exception classes
2. sqlite_vec_client/validation.py: Input validation utilities
3. test_security.py: Security test suite

Modified Files

1. sqlite_vec_client/base.py:

   • Added validation calls to all public methods
   • Enhanced error handling with try-catch blocks
   • Improved docstrings with Args, Returns, and Raises sections

2. sqlite_vec_client/init.py:

   • Exported all custom exceptions for public use

3. sqlite_vec_client/utils.py:

   • Updated to use f-string format specifiers (code quality improvement)

Testing

Created test_security.py with comprehensive tests:

• Table name validation (including SQL injection attempts)
• Input parameter validation
• Table not found error handling

All tests pass successfully.

Code Quality

• ✅ All code passes mypy type checking
• ✅ All code passes ruff linting
• ✅ Code formatted with ruff format
• ✅ Compatible with Python 3.9+

Usage Examples

Catching Specific Exceptions

from sqlite_vec_client import (
    SQLiteVecClient,
    TableNameError,
    ValidationError,
    TableNotFoundError,
)

# Handle invalid table name
try:
    client = SQLiteVecClient(table="invalid-name", db_path="db.db")
except TableNameError as e:
    print(f"Invalid table name: {e}")

# Handle validation errors
try:
    client = SQLiteVecClient(table="docs", db_path="db.db")
    client.create_table(dim=-1)  # Invalid dimension
except ValidationError as e:
    print(f"Validation error: {e}")

# Handle missing table
try:
    client = SQLiteVecClient(table="docs", db_path="db.db")
    client.similarity_search(embedding=[0.1, 0.2, 0.3])
except TableNotFoundError as e:
    print(f"Table not found: {e}")

Security Best Practices

1. Always validate user input: All table names and parameters are now validated
2. Use parameterized queries: All SQL queries use ? placeholders (already implemented)
3. Clear error messages: Users get helpful feedback without exposing internals
4. Fail fast: Invalid inputs are rejected immediately before any database operations

Next Steps

With the Critical Priority section complete, the project is now ready for:

• High Priority: Test Suite expansion
• High Priority: Example scripts
• High Priority: Documentation improvements