CVE-2025-7393: Drupal Mail Login Auth Bypass Vulnerability

CVE-2025-7393 Overview

CVE-2025-7393 is an Improper Restriction of Excessive Authentication Attempts vulnerability (CWE-307) affecting the Drupal Mail Login module. This security flaw allows attackers to perform brute force attacks against authentication endpoints without adequate rate limiting or lockout mechanisms. The vulnerability enables unauthorized actors to systematically attempt credential combinations until successful authentication is achieved, potentially compromising user accounts across affected Drupal installations.

Critical Impact
This vulnerability enables unrestricted brute force attacks against Drupal authentication systems, potentially leading to complete account compromise with high confidentiality, integrity, and availability impact.

Affected Products

mqanneh Mail Login versions 3.0.0 to before 3.2.0
mqanneh Mail Login versions 4.0.0 to before 4.2.0
Drupal sites utilizing the vulnerable Mail Login module

Discovery Timeline

2025-07-21 - CVE-2025-7393 published to NVD
2025-08-27 - Last updated in NVD database

Technical Details for CVE-2025-7393

Vulnerability Analysis

The Mail Login module for Drupal provides functionality that allows users to authenticate using their email address instead of a traditional username. The vulnerability stems from the module's failure to implement proper restrictions on authentication attempts. Without adequate rate limiting, account lockout policies, or CAPTCHA enforcement, the authentication endpoint becomes susceptible to automated credential guessing attacks.

When users attempt to log in via email, the module processes authentication requests without tracking or limiting the number of failed attempts from a single source. This architectural weakness allows attackers to iterate through password combinations at high speed, significantly increasing the probability of successful unauthorized access.

The network-accessible nature of this vulnerability means that any unauthenticated attacker with network access to the Drupal installation can exploit this flaw without requiring any prior privileges or user interaction.

Root Cause

The root cause of CVE-2025-7393 is the absence of proper authentication attempt restrictions within the Mail Login module. The module lacks implementation of standard brute force protection mechanisms such as:

Progressive delay between authentication attempts
Account lockout after consecutive failures
IP-based rate limiting
CAPTCHA integration for suspicious activity

This omission violates secure authentication design principles and allows unlimited login attempts without consequence.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can target the vulnerability by:

Identifying Drupal installations using the vulnerable Mail Login module
Automating login requests against the email-based authentication endpoint
Systematically attempting common passwords or using credential lists
Iterating through attempts without triggering defensive mechanisms
Achieving successful authentication upon password match

The attack can be conducted remotely against any internet-facing Drupal site running vulnerable versions of the Mail Login module. Due to the lack of rate limiting, attackers can achieve high request volumes, making password compromise highly probable for accounts with weak credentials.

Detection Methods for CVE-2025-7393

Indicators of Compromise

Unusually high volumes of failed login attempts from single IP addresses or IP ranges
Sequential login attempts against multiple user email addresses
Authentication requests occurring at automated/scripted intervals
Successful logins following multiple failed attempts from the same source

Detection Strategies

Implement web application firewall (WAF) rules to detect and alert on authentication abuse patterns
Monitor Drupal watchdog logs for excessive user.login.failed events
Configure SIEM rules to correlate failed authentication attempts by source IP and target account
Deploy anomaly detection for authentication endpoint request rates

Monitoring Recommendations

Enable verbose logging on authentication endpoints and review regularly
Set alerting thresholds for failed login attempt counts per account and per source IP
Monitor for credential stuffing patterns where multiple accounts are targeted in succession
Track geographic anomalies in login attempt sources

How to Mitigate CVE-2025-7393

Immediate Actions Required

Update Mail Login module to version 3.2.0 or later for the 3.x branch
Update Mail Login module to version 4.2.0 or later for the 4.x branch
Audit authentication logs for evidence of prior exploitation
Force password resets for accounts showing suspicious login activity

Patch Information

Patches are available through the official Drupal contributed modules repository. Affected organizations should immediately update to the patched versions as specified in the Drupal Security Advisory. The fix introduces proper authentication attempt restrictions to prevent brute force attacks.

Workarounds

Implement IP-based rate limiting at the web server or firewall level for login endpoints
Deploy CAPTCHA or similar challenge-response mechanisms on the login form
Enable two-factor authentication (2FA) for all user accounts to add a secondary authentication barrier
Consider temporarily disabling the Mail Login module until patching is complete

bash

# Example: Rate limiting with Nginx (temporary mitigation)
# Add to server block configuration
limit_req_zone $binary_remote_addr zone=login:10m rate=5r/m;

location /user/login {
    limit_req zone=login burst=3 nodelay;
    # existing proxy/fastcgi configuration
}