CVE-2026-4404: GoHarbor Auth Bypass Vulnerability

CVE-2026-4404 Overview

CVE-2026-4404 is a critical hardcoded credentials vulnerability affecting GoHarbor Harbor version 2.15.0 and below. This security flaw allows attackers to leverage default credentials to gain unauthorized access to the Harbor web UI, potentially compromising container registry operations and sensitive container images stored within the platform.

Critical Impact

Attackers can use well-known default credentials to gain administrative access to Harbor container registries, enabling unauthorized access to container images, potential supply chain attacks, and complete compromise of the registry infrastructure.

Affected Products

• GoHarbor Harbor version 2.15.0
• GoHarbor Harbor versions prior to 2.15.0

Discovery Timeline

• 2026-03-23 - CVE CVE-2026-4404 published to NVD
• 2026-03-24 - Last updated in NVD database

Technical Details for CVE-2026-4404

Vulnerability Analysis

This vulnerability stems from Harbor's use of hardcoded default credentials that persist after installation if administrators fail to change them. According to the Harbor Installation Documentation, the default administrator username and password are admin and Harbor12345 respectively. When these credentials remain unchanged, any attacker with network access to the Harbor instance can authenticate with full administrative privileges.

The vulnerability is classified under CWE-798: Use of Hard-coded Credentials, which represents a fundamental security design flaw. Harbor, being a cloud-native container registry used to store, sign, and scan container images, presents a high-value target for attackers seeking to compromise software supply chains.

Root Cause

The root cause of this vulnerability lies in Harbor's default configuration that ships with predictable, well-documented credentials. The configuration file harbor.yml contains the default password, and if administrators do not modify this value during or after installation, the system remains vulnerable. This represents a failure to implement secure-by-default principles, as the installation process does not enforce credential changes before allowing the system to become operational.

Attack Vector

The attack vector for CVE-2026-4404 is network-based and requires no prior authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying Harbor instances exposed to the network (commonly on ports 80 or 443)
2. Navigating to the Harbor web UI login page
3. Attempting authentication with the default credentials (admin / Harbor12345)
4. Upon successful authentication, gaining full administrative access to the container registry

The exploitation is trivial and can be automated at scale to discover vulnerable Harbor instances across the internet. Once access is obtained, attackers can pull proprietary container images, push malicious images, modify existing images, or delete critical registry data.

Detection Methods for CVE-2026-4404

Indicators of Compromise

• Successful authentication events for the admin account from unexpected IP addresses or geographic locations
• Multiple failed login attempts followed by a successful login using default credentials
• Unusual API activity or image pulls/pushes from the administrator account
• Creation of new user accounts or modification of access control policies by the admin user

Detection Strategies

• Implement authentication monitoring to alert on successful logins using the default admin account
• Deploy network monitoring to detect access attempts to Harbor instances from untrusted networks
• Use vulnerability scanners configured to check for default credentials on Harbor installations
• Review Harbor audit logs for administrative actions performed outside of normal maintenance windows

Monitoring Recommendations

• Enable and centralize Harbor audit logging to a SIEM solution for correlation and alerting
• Configure alerts for authentication events involving the default administrator account
• Monitor for reconnaissance activities targeting Harbor ports and endpoints
• Implement network segmentation monitoring to detect lateral movement from compromised registries

How to Mitigate CVE-2026-4404

Immediate Actions Required

• Change the default administrator password immediately on all Harbor installations
• Audit all Harbor instances to verify default credentials have been replaced with strong, unique passwords
• Review user accounts and remove any unauthorized accounts that may have been created
• Enable Harbor's built-in audit logging to track administrative actions
• Restrict network access to Harbor instances using firewalls or network segmentation

Patch Information

GoHarbor has addressed this issue through improved installation guidance and security recommendations. Refer to the GitHub Pull Request for details on the remediation approach. The CERT Vulnerability Note provides additional guidance on securing Harbor deployments. Organizations should ensure they are running the latest Harbor version and have followed all security hardening procedures.

Workarounds

• Modify the harbor.yml configuration file to set a strong, unique administrator password before running the installer
• Use environment variables or secrets management solutions to inject credentials during deployment
• Implement network-level access controls to restrict Harbor access to trusted networks only
• Deploy a reverse proxy with additional authentication layers in front of Harbor
• Consider disabling or renaming the default admin account after creating alternative administrative accounts

# Configuration example
# In harbor.yml, change the default password before installation:
harbor_admin_password: <STRONG_UNIQUE_PASSWORD>

# After installation, change password via Harbor CLI:
harbor-cli user update-password --username admin --old-password Harbor12345 --new-password <NEW_SECURE_PASSWORD>

# Restrict network access using firewall rules (example with iptables):
iptables -A INPUT -p tcp --dport 443 -s <TRUSTED_NETWORK_CIDR> -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP