CVE-2026-26744: FormaLMS Information Disclosure Flaw

CVE-2026-26744 Overview

A user enumeration vulnerability exists in FormaLMS 4.1.18 and below in the password recovery functionality accessible via the /lostpwd endpoint. The application returns different error messages for valid and invalid usernames, allowing an unauthenticated attacker to determine which usernames are registered in the system through observable response discrepancy. This type of information disclosure vulnerability can be leveraged by attackers to build a list of valid user accounts for subsequent targeted attacks such as password spraying, credential stuffing, or social engineering campaigns.

Critical Impact

Unauthenticated attackers can enumerate valid usernames in FormaLMS installations, enabling targeted credential attacks and reducing the effort required for account compromise.

Affected Products

• FormaLMS version 4.1.18 and below
• FormaLMS installations with password recovery functionality enabled
• Systems exposing the /lostpwd endpoint

Discovery Timeline

• 2026-02-19 - CVE CVE-2026-26744 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-26744

Vulnerability Analysis

This vulnerability falls under the Information Disclosure category, specifically user enumeration through response discrepancy. The password recovery mechanism in FormaLMS fails to implement consistent response handling, which allows attackers to distinguish between valid and invalid usernames without authentication.

When a user submits a password reset request through the /lostpwd endpoint, the application processes the request and returns a response that differs based on whether the submitted username exists in the database. This behavioral difference—whether through distinct error messages, response timing, HTTP status codes, or page content—provides an oracle that attackers can query to systematically enumerate valid accounts.

User enumeration vulnerabilities, while sometimes considered lower severity in isolation, represent a significant reconnaissance capability. They reduce the attack surface for brute-force attempts by eliminating guesswork about valid targets and enable more convincing phishing attacks by confirming which email addresses or usernames are associated with the target organization's LMS deployment.

Root Cause

The root cause of this vulnerability lies in the application's failure to implement consistent response behavior in the password recovery workflow. The backend logic likely contains conditional branches that return different error messages or responses based on database lookup results—one path for when a username is found and another when it is not. Secure implementations should return identical responses regardless of whether the username exists, typically with a generic message such as "If this account exists, a password reset link has been sent."

Attack Vector

The attack can be executed remotely by any unauthenticated user with network access to the FormaLMS installation. An attacker would:

1. Access the password recovery page at the /lostpwd endpoint
2. Submit requests with candidate usernames (e.g., common names, email patterns, or harvested identifiers)
3. Analyze the application responses for discrepancies indicating valid versus invalid accounts
4. Compile a list of confirmed valid usernames for use in subsequent attacks

This can be automated using simple scripts to rapidly test large lists of potential usernames, making it trivial to enumerate hundreds or thousands of accounts in a short period.

The vulnerability mechanism involves submitting requests to the password recovery endpoint and observing response differences. Technical details and proof-of-concept demonstrations are available in the GitHub PoC repository.

Detection Methods for CVE-2026-26744

Indicators of Compromise

• High volume of requests to the /lostpwd endpoint from a single source IP
• Sequential or rapid requests to password recovery with different usernames
• Automated tool signatures in User-Agent strings or request patterns
• Failed password reset attempts for non-existent users followed by attempts on valid accounts

Detection Strategies

• Implement rate limiting detection on the /lostpwd endpoint to identify enumeration attempts
• Monitor web application logs for anomalous patterns in password reset request frequency
• Configure web application firewall (WAF) rules to detect and block automated enumeration tools
• Set up alerts for password reset requests exceeding normal baseline thresholds

Monitoring Recommendations

• Enable detailed logging for all authentication and password recovery endpoints
• Establish baseline metrics for normal password reset request volumes
• Implement real-time alerting for request rate anomalies to sensitive endpoints
• Correlate password reset enumeration attempts with subsequent login failures

How to Mitigate CVE-2026-26744

Immediate Actions Required

• Update FormaLMS to the latest version if a patched release is available
• Implement rate limiting on the /lostpwd endpoint to slow enumeration attempts
• Configure web application firewall rules to detect and block automated enumeration
• Review and audit user accounts for any signs of compromise or unauthorized access

Patch Information

Administrators should monitor the FormaLMS GitHub repository for security updates and patches addressing this vulnerability. Ensure your installation is updated to the latest available version that includes fixes for user enumeration issues in the password recovery functionality.

Workarounds

• Implement CAPTCHA or similar challenge-response mechanisms on the password recovery form
• Configure rate limiting at the web server or reverse proxy level for the /lostpwd endpoint
• Modify error messages to be generic and identical regardless of username validity
• Consider implementing account lockout or progressive delays after multiple recovery attempts
• Deploy a WAF with rules specifically designed to detect and block enumeration attempts

# Example: Rate limiting configuration for nginx
# Add to your server block configuration

location /lostpwd {
    # Limit requests to 5 per minute per IP
    limit_req zone=password_reset burst=5 nodelay;
    
    # Standard proxy/fastcgi configuration
    proxy_pass http://formalms_backend;
}

# Define the rate limit zone in http block
# limit_req_zone $binary_remote_addr zone=password_reset:10m rate=5r/m;