CVE-2026-28766: Gardyn Information Disclosure Flaw

CVE-2026-28766 Overview

CVE-2026-28766 is a critical authentication bypass vulnerability affecting Gardyn smart garden devices. A specific endpoint exposes all user account information for registered Gardyn users without requiring authentication. This Missing Authentication for Critical Function (CWE-306) vulnerability allows remote attackers to access sensitive user data through the network without any credentials.

Critical Impact

Unauthenticated remote attackers can access all registered user account information, potentially leading to mass data exposure, account takeover, and privacy violations for Gardyn device users.

Affected Products

• Gardyn Smart Garden Devices
• My Gardyn Cloud Services

Discovery Timeline

• 2026-04-03 - CVE CVE-2026-28766 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-28766

Vulnerability Analysis

This vulnerability represents a fundamental authentication failure in the Gardyn platform's API architecture. The affected endpoint fails to implement any authentication mechanism, allowing anonymous access to user account data. This type of missing authentication for critical function (CWE-306) is particularly severe in IoT ecosystems where devices are constantly connected and user data may include sensitive personal information, device configurations, and usage patterns.

The vulnerability enables attackers to enumerate and exfiltrate user account information without needing valid credentials. Given the network-accessible nature of this endpoint and the lack of any prerequisite user interaction, exploitation is straightforward and can be performed at scale.

Root Cause

The root cause of CVE-2026-28766 is missing authentication for a critical function (CWE-306). The vulnerable endpoint was deployed without implementing proper authentication checks, allowing any network-accessible request to retrieve user account information. This represents a fundamental access control failure in the API design where authorization controls were either not implemented or were bypassed during development.

Attack Vector

The attack vector for this vulnerability is network-based with low complexity. An attacker can exploit this vulnerability by:

1. Identifying the vulnerable API endpoint through reconnaissance or documentation analysis
2. Sending unauthenticated HTTP requests directly to the endpoint
3. Receiving user account information in the response without any credential verification
4. Iterating through requests to enumerate all registered user accounts

The attack requires no privileges, no user interaction, and can be executed remotely from any network location with access to the Gardyn service. For detailed technical information, refer to the CISA ICS Advisory ICSA-26-055-03.

Detection Methods for CVE-2026-28766

Indicators of Compromise

• Unusual spikes in API requests to user data endpoints from single IP addresses or unusual geographic locations
• Mass enumeration patterns in web server logs showing sequential or bulk requests for user information
• Authentication bypass attempts visible in application logs where user data is returned without session tokens
• Network traffic anomalies showing data exfiltration volumes inconsistent with normal user activity

Detection Strategies

• Monitor API gateway logs for requests to sensitive endpoints that lack authentication headers or tokens
• Implement rate limiting detection to identify potential data scraping or enumeration attempts
• Deploy web application firewall (WAF) rules to detect and alert on unauthenticated access patterns to user data endpoints
• Configure SIEM correlation rules to identify authentication bypass patterns across multiple log sources

Monitoring Recommendations

• Enable detailed access logging on all API endpoints handling user data
• Implement real-time alerting for successful requests to user data endpoints without valid authentication tokens
• Monitor for unusual data transfer volumes from API services that could indicate bulk data exfiltration
• Review network flow data for connections to known attacker infrastructure or unusual destination IP addresses

How to Mitigate CVE-2026-28766

Immediate Actions Required

• Review all API endpoints for proper authentication implementation and immediately remediate any unauthenticated access to sensitive data
• Implement network-level access controls to restrict access to the vulnerable endpoint until a patch is available
• Enable additional logging and monitoring on user data endpoints to detect potential exploitation attempts
• Notify affected users about the potential data exposure and recommend password changes for accounts that may have been compromised

Patch Information

Organizations should consult the My Gardyn Security Overview and the CISA ICS Advisory ICSA-26-055-03 for the latest patch information and vendor guidance. Technical details are also available in the GitHub CSAF JSON File.

Workarounds

• Implement network segmentation to isolate IoT devices from critical infrastructure and limit exposure
• Deploy a reverse proxy with authentication enforcement in front of the vulnerable endpoint
• Use firewall rules to restrict access to the affected service to trusted IP ranges only
• Consider temporarily disabling the vulnerable endpoint if user data access is not critical to operations

# Example: Restrict access to vulnerable endpoint via iptables
# Replace <SERVICE_PORT> with the actual port number
iptables -A INPUT -p tcp --dport <SERVICE_PORT> -s <TRUSTED_IP_RANGE> -j ACCEPT
iptables -A INPUT -p tcp --dport <SERVICE_PORT> -j DROP