Grav Admin Plugin vulnerable to User Enumeration & Email Disclosure

Grav v1.7.49.5 / Admin v1.10.49.1 – User Enumeration & Email Disclosure

Summary

A user enumeration and email disclosure vulnerability exists in Grav v1.7.49.5 with Admin plugin v1.10.49.1.
The "Forgot Password" functionality at /admin/forgot leaks information about valid usernames and their associated email addresses through distinct server responses.
This allows an attacker to enumerate users and disclose sensitive email addresses, which can be leveraged for targeted attacks such as password spraying, phishing, or social engineering.

Details

The issue resides in the taskForgot() function, which handles the forgot password workflow.
Relevant vulnerable logic:

if (null === $user || $user->state !== 'enabled' || !$to) {
    ...
    // Generic message for invalid/non-existing users
    $this->setMessage($this->translate('PLUGIN_ADMIN.FORGOT_INSTRUCTIONS_SENT_VIA_EMAIL'));
    return $this->createRedirectResponse($current);
}

if ($rateLimiter->isRateLimited($username)) {
    ...
    $interval = $config->get('plugins.login.max_pw_resets_interval', 2);

    // Sensitive message for valid users
    $this->setMessage($this->translate('PLUGIN_LOGIN.FORGOT_CANNOT_RESET_IT_IS_BLOCKED', $to, $interval), 'error');

    return $this->createRedirectResponse($current);
}

When an attacker submits the password reset form at /admin/forgot with an invalid username, the application responds with:

Instructions to reset your password have been sent to your email address

However, when a valid username is supplied, and the attacker repeatedly triggers password reset requests, the application responds with:

Cannot reset password for <USER_EMAIL>, password reset functionality temporarily blocked, please try later (maximum 60 minutes)

This discrepancy in responses enables:

1. User Enumeration – Attackers can determine if a username exists in the system by analyzing the response.
2. User Email Disclosure – The system discloses the actual email address associated with the account (e.g., admin@localhost.test).

This violates best practices for authentication flows, where responses should remain generic to avoid leaking sensitive information.

PoC

1. Navigate to the Forgot Password page: https://<target>/admin/forgot
2. Submit a reset request with a random/invalid username (e.g., invalid_user):

• Response:

  Instructions to reset your password have been sent to your email address
  

3. Submit a reset request with a valid username (e.g., admin).
4. Repeatedly request a reset for the same username until the lockout mechanism triggers.

• Response:

  Cannot reset password for admin@localhost.test, password reset functionality temporarily blocked, please try later (maximum 60 minutes)
  

5. Observe the leaked email address of the admin account in the error message.

Impact

• Severity: Medium
• Type: Information Disclosure / User Enumeration
• Who is Impacted: All Grav sites using Admin plugin v1.10.49.1 with password reset enabled.
• Risks:
  • Allows attackers to enumerate valid usernames.
  • Exposes email addresses of admin accounts, which can be used in:
  • Credential stuffing
  • Password spraying
  • Phishing/social engineering campaigns
  • Further exploitation in combination with other vulnerabilities

Recommendation

• Modify the taskForgot() logic to always return a generic, non-identifying message, regardless of whether the username exists or rate limits are hit.

• Example safe response:

  If the account exists, password reset instructions will be sent.
  

• Do not include email addresses ($to) or other sensitive data in error messages.