What best practices should be followed when implementing a BBCode parser in a PHP application to avoid security vulnerabilities?

When implementing a BBCode parser in a PHP application, it is crucial to sanitize user input to prevent security vulnerabilities such as cross-site scripting (XSS) attacks. One way to achieve this is by using the `htmlspecialchars` function to encode special characters in the user input before parsing and rendering the BBCode content. 

// Sanitize user input before parsing BBCode
$userInput = htmlspecialchars($_POST['user_input']);

// Parse BBCode content
$bbcodeParser = new BBCodeParser();
$parsedContent = $bbcodeParser->parse($userInput);

// Display parsed content
echo $parsedContent;

Keywords

XSS SQL injection whitelist htmlentities preg_replace

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