CVE-2026-25509: CI4MS Email Enumeration Vulnerability

CVE-2026-25509 Overview

CVE-2026-25509 is an information disclosure vulnerability affecting CI4MS, a CodeIgniter 4-based CMS skeleton designed for production-ready modular architecture with RBAC authorization and theme support. The vulnerability exists in the authentication implementation, specifically within the password reset process, where the application's response behavior allows unauthenticated attackers to enumerate valid email addresses registered in the system.

Critical Impact

Attackers can determine whether specific email addresses are registered in the CI4MS application without authentication, enabling targeted phishing attacks, credential stuffing, and social engineering campaigns against confirmed users.

Affected Products

• CI4MS versions prior to 0.28.5.0
• CodeIgniter 4-based CMS deployments using vulnerable CI4MS authentication modules
• Systems utilizing CI4MS password reset functionality

Discovery Timeline

• 2026-02-03 - CVE CVE-2026-25509 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-25509

Vulnerability Analysis

This email enumeration vulnerability (CWE-204: Observable Response Discrepancy) occurs when the CI4MS authentication system provides distinguishable responses based on whether an email address exists in the user database during the password reset workflow. When an attacker submits a password reset request, the application responds differently for registered versus unregistered email addresses, allowing systematic enumeration of valid user accounts.

The vulnerability is exploitable remotely over the network without requiring any authentication or privileges. No user interaction is needed to exploit this flaw, making it particularly dangerous for automated reconnaissance activities. While the confidentiality impact is limited to user email enumeration, this information serves as a critical stepping stone for more sophisticated attacks.

Root Cause

The root cause stems from improper implementation of the password reset functionality in CI4MS. The application fails to normalize its response behavior when processing password reset requests, creating an observable discrepancy that reveals the existence of user accounts. Secure implementations should return identical responses regardless of whether the submitted email address is registered, preventing attackers from distinguishing between valid and invalid accounts.

Attack Vector

The attack exploits the network-accessible password reset endpoint. An attacker can systematically submit password reset requests using a list of target email addresses and analyze the application's responses to identify which addresses correspond to registered accounts. This enumeration can be performed at scale using automated tools, allowing attackers to compile lists of valid user accounts for subsequent targeted attacks.

The vulnerability manifests through response discrepancies in the password reset process. When a registered email is submitted, the application may return a different message, HTTP status code, response time, or page behavior compared to an unregistered email. Attackers leverage these observable differences to enumerate users. For technical implementation details, see the GitHub Security Advisory GHSA-654x-9q7r-g966.

Detection Methods for CVE-2026-25509

Indicators of Compromise

• High volume of password reset requests originating from single IP addresses or address ranges
• Sequential or pattern-based email addresses being submitted to the password reset endpoint
• Automated request patterns with consistent timing intervals to the authentication endpoints
• Unusual geographic distribution of password reset requests

Detection Strategies

• Monitor authentication logs for abnormal spikes in password reset request volume
• Implement rate limiting detection on the password reset endpoint to identify enumeration attempts
• Configure alerting for sequential failed password reset attempts from the same source
• Deploy web application firewall (WAF) rules to detect and block automated enumeration tools

Monitoring Recommendations

• Enable detailed logging for all authentication-related endpoints including password reset functionality
• Implement anomaly detection for request patterns to the /password/reset or equivalent endpoints
• Monitor for reconnaissance activity preceding credential stuffing or phishing campaigns
• Track correlation between enumeration attempts and subsequent targeted attacks against identified users

How to Mitigate CVE-2026-25509

Immediate Actions Required

• Upgrade CI4MS to version 0.28.5.0 or later immediately
• Implement rate limiting on password reset endpoints to slow enumeration attempts
• Deploy CAPTCHA or similar challenge-response mechanisms on the password reset form
• Monitor authentication logs for evidence of prior enumeration attempts

Patch Information

The vulnerability has been addressed in CI4MS version 0.28.5.0. The fix normalizes application responses during the password reset process to eliminate observable discrepancies. The specific remediation can be reviewed in the GitHub Commit 86be293. Organizations should update to this version or later to resolve the vulnerability.

Workarounds

• Implement a generic response message for all password reset requests regardless of email validity (e.g., "If this email is registered, you will receive a reset link")
• Add rate limiting to restrict password reset requests to a maximum of 3-5 attempts per IP address per hour
• Deploy CAPTCHA challenges after initial password reset requests to prevent automated enumeration
• Consider implementing account lockout notifications to alert users of potential enumeration targeting their accounts

# Example rate limiting configuration for nginx
# Add to location block handling password reset endpoint
limit_req_zone $binary_remote_addr zone=password_reset:10m rate=5r/m;

location /password/reset {
    limit_req zone=password_reset burst=3 nodelay;
    # Additional proxy/handler configuration
}