How can the use of strip_tags() function in PHP impact the security of a web application?

Using the strip_tags() function in PHP can impact the security of a web application by potentially leaving the application vulnerable to cross-site scripting (XSS) attacks. This function removes all HTML and PHP tags from a string, which can inadvertently strip out necessary tags and attributes needed for security measures like input validation and output encoding. To mitigate this risk, it is recommended to use a more targeted approach to sanitizing user input, such as using HTMLPurifier or a custom function that allows specific tags and attributes. 

// Example of using HTMLPurifier to sanitize user input
require_once 'path/to/htmlpurifier/library/HTMLPurifier.auto.php';
$config = HTMLPurifier_Config::createDefault();
$purifier = new HTMLPurifier($config);

$dirty_html = "<script>alert('XSS attack!')</script>";
$clean_html = $purifier->purify($dirty_html);

echo $clean_html;

Keywords

strip_tags security web application PHP function

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