Regular expressions are patterns used to match and manipulate strings based on specific rules.
The pattern provided to PHP regular expression functions is required to be enclosed in valid delimiters to be working correctly.
What is the potential impact?
Failing to enclose the pattern with valid delimiters will result in a PHP warning and the pattern never matching. Since the warning only appears
during runtime when the pattern is evaluated, such a mistake risks to get unnoticed into production.
The use of suppressed warnings in PHP can further complicate this issue. As regex pattern are often used for validation or sanitization, the
suppress warnings feature can obscure any problems regarding incorrect patterns. As the incorrect patterns are not recognized and have no effect, this
could lead to more serious security issues.
