XSS Payload Pattern (Basic Detection) Regex for PHP

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching xss payload pattern (basic detection), ported and verified for PHP. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// XSS Payload Pattern (Basic Detection)
// ReDoS-safe | RegexVault — Security > Injection Patterns

define('XSS_PAYLOAD_PATTERN_BASIC_DETECTION_PATTERN', '/(?:<script[\s>]|<\\/script>|javascript:|vbscript:|onload\s*=|onerror\s*=|onclick\s*=|onmouseover\s*=|<iframe\b|<object\b|<embed\b|<svg[\s>]|document\.cookie|document\.write|eval\s*\(|setTimeout\s*\(|setInterval\s*\(|window\.location|alert\s*\(|confirm\s*\(|prompt\s*\(|data:text\/html)/');

function validate_xss_payload_pattern_basic_detection(string $input): bool {
    return (bool) preg_match(XSS_PAYLOAD_PATTERN_BASIC_DETECTION_PATTERN, $input);
}

// Example
var_dump(validate_xss_payload_pattern_basic_detection("<script>alert(1)</script>")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Security > Injection Patterns category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Basic XSS detection. Incomplete — XSS payloads can be encoded in dozens of ways (HTML entities, Unicode escapes, UTF-7, etc.). Use as a signal for logging/alerting. The real defense is output encoding via a template engine (React, Vue, Jinja2 with auto-escaping).