What potential issue can arise when using regular expressions in PHP?

One potential issue when using regular expressions in PHP is the presence of special characters that may cause unexpected behavior or errors. To solve this issue, it is recommended to use the preg_quote() function to escape any special characters in the regular expression pattern before using it. 

$pattern = '/[a-z]+/';
$escaped_pattern = preg_quote($pattern, '/');
// Now use the escaped pattern in your regular expression functions

Keywords

Regular expressions PHP backtracking catastrophic denial of service

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