CVE-2026-28767: Authentication Bypass Vulnerability

CVE-2026-28767 Overview

CVE-2026-28767 is an authentication bypass vulnerability where a specific administrative endpoint for notifications is accessible without proper authentication. This vulnerability, classified under CWE-306 (Missing Authentication for Critical Function), allows unauthenticated remote attackers to access administrative functionality that should require proper credentials.

Critical Impact

Unauthenticated attackers can access administrative notification endpoints over the network, potentially exposing sensitive system information or enabling unauthorized administrative actions.

Affected Products

• MyGardyn IoT/OT Systems (specific versions not disclosed)

Discovery Timeline

• 2026-04-03 - CVE CVE-2026-28767 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-28767

Vulnerability Analysis

This vulnerability represents a fundamental security flaw in the authentication architecture of the affected system. The administrative notifications endpoint lacks the necessary authentication controls that should gate access to privileged functionality. An attacker can reach this endpoint directly over the network without providing any credentials, bypassing the intended access control mechanisms entirely.

The CWE-306 classification indicates that the application fails to perform any authentication check before allowing access to the critical administrative function. This type of vulnerability is particularly concerning in Industrial Control Systems (ICS) and Operational Technology (OT) environments, as indicated by the CISA ICS Advisory associated with this vulnerability.

Root Cause

The root cause of this vulnerability is missing authentication for a critical function (CWE-306). The administrative notifications endpoint was implemented without the required authentication middleware or access control checks, allowing any network-adjacent or remote attacker to access the endpoint directly.

This represents a design flaw where security controls were either omitted during development or improperly configured, leaving the administrative functionality exposed to unauthenticated access.

Attack Vector

The attack vector is network-based, requiring no user interaction and no prior privileges. An attacker with network access to the vulnerable endpoint can directly access the administrative notifications functionality without any authentication.

The attack flow typically involves:

1. Identifying the target system with the exposed administrative endpoint
2. Sending direct HTTP requests to the notifications administrative endpoint
3. Accessing administrative notification data or functionality without providing credentials
4. Potentially leveraging the exposed information for further attacks

Since no code examples are available for this vulnerability, administrators should consult the CISA ICS Advisory ICSA-26-055-03 for detailed technical information about the vulnerability mechanism.

Detection Methods for CVE-2026-28767

Indicators of Compromise

• Unusual HTTP requests to administrative notification endpoints from unauthorized IP addresses
• Access logs showing administrative endpoint access without corresponding authentication events
• Anomalous traffic patterns targeting the notifications API without prior login sessions
• Unexpected queries or data extraction from the notifications subsystem

Detection Strategies

• Implement network monitoring to detect unauthenticated requests to administrative endpoints
• Deploy web application firewalls (WAF) with rules to detect and block unauthenticated administrative access attempts
• Enable detailed access logging on all administrative endpoints and correlate with authentication logs
• Use SentinelOne Singularity to monitor for anomalous process behavior and unauthorized API access patterns

Monitoring Recommendations

• Review access logs for the notifications administrative endpoint for any unauthorized access
• Monitor network traffic for direct requests to administrative endpoints bypassing authentication flows
• Set up alerts for administrative endpoint access from external or unexpected IP ranges
• Implement anomaly detection for API access patterns that deviate from authenticated user baselines

How to Mitigate CVE-2026-28767

Immediate Actions Required

• Restrict network access to the administrative notifications endpoint using firewall rules or network segmentation
• Implement authentication requirements on all administrative endpoints immediately
• Review and audit all administrative endpoints for similar authentication bypass vulnerabilities
• Monitor for any signs of exploitation while remediation is in progress

Patch Information

Consult the MyGardyn Security Page for official patch information and updates. Additionally, review the CISA ICS Advisory ICSA-26-055-03 for vendor-recommended remediation steps and the GitHub CSAF Document for structured vulnerability data.

Workarounds

• Implement network segmentation to isolate affected systems from untrusted networks
• Deploy a reverse proxy with authentication enforcement in front of the vulnerable endpoint
• Use firewall rules to allow access to administrative endpoints only from trusted management networks
• Enable VPN requirements for all administrative access until patches are applied

# Example network segmentation configuration (iptables)
# Restrict access to administrative endpoints to management network only
iptables -A INPUT -p tcp --dport 443 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP