CVE-2026-24038 Overview
CVE-2026-24038 is an authentication bypass vulnerability in Horilla, a free and open source Human Resource Management System (HRMS). The vulnerability exists in version 1.4.0 where the OTP (One-Time Password) handling logic contains a flawed equality check that can be exploited to bypass two-factor authentication entirely without providing a valid OTP.
Critical Impact
Attackers can bypass two-factor authentication to gain unauthorized access to HR systems, potentially compromising sensitive employee data, manipulating records, and enabling system-wide abuse. Administrative account compromise poses the highest risk.
Affected Products
- Horilla HRMS version 1.4.0
Discovery Timeline
- 2026-01-22 - CVE CVE-2026-24038 published to NVD
- 2026-01-22 - Last updated in NVD database
Technical Details for CVE-2026-24038
Vulnerability Analysis
This vulnerability is classified under CWE-287 (Improper Authentication) and represents a critical flaw in how Horilla handles OTP verification during the authentication process. The root cause lies in a flawed equality comparison that fails to properly validate OTP presence and expiration states.
When an OTP expires on the server, the system returns None as the stored OTP value. The vulnerability arises because if an attacker crafts a POST request that omits the otp field entirely, the user-supplied OTP value also evaluates to None. When the comparison user_otp == otp is executed, both values are None, causing the check to pass and the authentication to succeed without any valid OTP being provided.
This authentication bypass is particularly dangerous because it completely negates the security benefits of two-factor authentication. Attackers who have obtained or compromised a user's primary credentials (username and password) can then bypass the second authentication factor by simply waiting for any existing OTP to expire and submitting a login request without the OTP field.
Root Cause
The root cause is improper input validation and flawed logic in the OTP verification mechanism. The application fails to:
- Explicitly check whether an OTP was provided in the request
- Distinguish between an expired OTP (None) and a missing OTP field (also None)
- Implement proper null/undefined handling before performing the equality comparison
The vulnerable code path allows the authentication flow to proceed when both the server-side OTP (expired) and client-side OTP (omitted) resolve to the same falsy value.
Attack Vector
The attack is network-based and requires low privileges—specifically, valid primary credentials (username and password) for the target account. The attacker must:
- Obtain valid primary credentials for a target account through phishing, credential stuffing, or other means
- Initiate a login request with valid credentials to trigger OTP generation
- Wait for the OTP to expire on the server (causing the stored value to become None)
- Submit a subsequent authentication request without including the otp field in the POST body
- The comparison None == None evaluates to True, granting access
The attack mechanism exploits the implicit type coercion and the failure to explicitly validate OTP presence. By omitting the OTP parameter entirely from the request body rather than sending an empty or invalid value, the attacker ensures that the user-supplied value resolves to None, matching the expired server-side OTP.
Detection Methods for CVE-2026-24038
Indicators of Compromise
- Authentication success events where the OTP field is absent or null in the request logs
- Login patterns showing successful 2FA bypasses after initial OTP generation requests
- Multiple authentication attempts from the same source with delayed timing between initial login and 2FA completion
Detection Strategies
- Monitor authentication logs for successful logins where the OTP parameter is missing from the request payload
- Implement alerting on authentication requests that succeed without all expected 2FA fields present
- Analyze web application firewall (WAF) logs for POST requests to authentication endpoints lacking the otp field
- Review application logs for patterns indicating OTP expiration followed by successful authentication
Monitoring Recommendations
- Enable detailed logging for all authentication-related endpoints including the full request payload structure
- Configure SIEM rules to correlate OTP generation events with subsequent authentication success events
- Implement anomaly detection for authentication patterns that deviate from expected 2FA workflows
- Monitor for bulk authentication attempts that may indicate exploitation at scale
How to Mitigate CVE-2026-24038
Immediate Actions Required
- Upgrade Horilla HRMS to version 1.5.0 or later immediately
- Review authentication logs for any evidence of exploitation prior to patching
- Force password resets for any accounts showing suspicious authentication patterns
- Temporarily disable or increase scrutiny on accounts with elevated privileges until patching is complete
Patch Information
The vulnerability has been fixed in Horilla HRMS version 1.5.0. Organizations should upgrade to this version or later to remediate the vulnerability. The patch information is available through the GitHub Release 1.5.0. Additional details about the vulnerability are documented in the GitHub Security Advisory GHSA-hqpv-ff5v-3hwf.
Workarounds
- Implement network-level access controls to restrict authentication endpoints to trusted IP ranges
- Deploy a web application firewall (WAF) rule to reject authentication requests that lack the required otp field
- Enable additional logging and monitoring on authentication endpoints to detect exploitation attempts
- Consider implementing IP-based rate limiting on authentication endpoints to slow potential attacks
# Example WAF rule concept for blocking requests without OTP field
# This is a conceptual example - actual implementation depends on your WAF solution
# Block POST requests to login endpoint that lack 'otp' parameter
# Consult your WAF documentation for proper syntax and configuration
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
