Overview
CVE-2017-9303 describes a security misconfiguration in Laravel 5.4.x before 5.4.22 where the host portion of the password reset URL was not properly constrained. This allowed an attacker to influence the host in the reset link, creating a phishing surface where victims could be sent to a domain controlled by the attacker. The result could be users entering credentials on a spoofed site that looks like the legitimate reset page, enabling credential theft or token leakage. This class of issue stems from improper handling of host/name resolution in URL generation, classified under CWE-20 ( Improper Handling of Incorrect/Inappropriate Input ). In real-world Laravel deployments, if the app URL or host is not strictly validated or canonicalized, adversaries could craft links that point to an attacker-controlled host even when tokens are otherwise protected. The vulnerability highlights the importance of using a trusted, canonical host when generating authentication-related links and validating that host in multi-tenant or proxy-rich environments.
Affected Versions
Laravel 5.4.x before 5.4.22 (i.e., 5.4.0 - 5.4.21)
Code Fix Example
Laravel API Security Remediation
Vulnerable:
<?php
// Vulnerable pattern: host can be influenced by user input when constructing a reset URL
$host = isset($_GET['host']) ? $_GET['host'] : $_SERVER['HTTP_HOST'];
$token = 'TOKEN';
$email = '[email protected]';
$resetUrl = 'http://' . $host . '/password/reset?token=' . $token . '&email=' . urlencode($email);
// Send $resetUrl in reset email
Fixed:
<?php
use Illuminate\\Support\\Facades\\URL;
$token = 'TOKEN';
$email = '[email protected]';
// Fixed pattern: URL is generated using the application's canonical host from config/app.url
$resetUrl = URL::to('/password/reset', ['token' => $token, 'email' => $email], true);
// Send $resetUrl in reset email