CVV / CVC / Security Code Regex for PHP

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching cvv / cvc / security code, ported and verified for PHP. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. 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
// CVV / CVC / Security Code
// ReDoS-safe | RegexVault — Finance > Card Numbers

define('CVV_CVC_SECURITY_CODE_PATTERN', '/^[0-9]{3,4}$/');

function validate_cvv_cvc_security_code(string $input): bool {
    return (bool) preg_match(CVV_CVC_SECURITY_CODE_PATTERN, $input);
}

// Example
var_dump(validate_cvv_cvc_security_code("123")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Card Numbers 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

CVV (Visa), CVC (Mastercard), CID (Amex) are 3 digits on the back for Visa/MC/Discover, 4 digits on the front for Amex. PCI-DSS prohibits storing CVV/CVC post-authorization — never persist this value.