CVE-2026-16771 in Arris BGW210-700
Summary
by MITRE • 07/28/2026
In firmware versions 2.7.7 and earlier, the Arris BGW210‑700 gateway fails to enforce any server‑side authentication on its /cgi-bin/*.ha management endpoints, relying solely on client‑side CSS/JavaScript gating that can be bypassed by any HTTP client. This allows unauthenticated attackers on the LAN to read sensitive configuration data, modify persistent device settings, or trigger backend diagnostic operations. The issue appears systemic across the CGI handler chain.
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Analysis
by VulDB Data Team • 07/28/2026
The vulnerability identified in Arris BGW210-700 gateway firmware versions 2.7.7 and earlier represents a critical authentication bypass flaw that undermines fundamental security controls within the device's management interface. This issue stems from a failure to implement proper server-side validation mechanisms, instead relying entirely on client-side enforcement through CSS and JavaScript controls that can be easily circumvented by any HTTP client. The affected /cgi-bin/*.ha management endpoints serve as entry points for administrative functions that should only be accessible to authenticated users with proper authorization credentials.
The technical implementation flaw manifests as a complete absence of server-side authentication checks, creating a pathway for unauthorized access to sensitive device configuration data and operational controls. This vulnerability operates at the application layer and directly violates security principle 4 from the OWASP Top Ten 2017, which addresses broken authentication mechanisms. The lack of proper session management and authorization validation creates an environment where any local network user can exploit these endpoints without requiring valid credentials or privileges. The bypass capability extends beyond simple data reading to include modification of persistent device settings and execution of backend diagnostic operations that could potentially disrupt service or expose additional attack vectors.
From an operational impact perspective, this vulnerability presents significant risk to organizations relying on these devices for network infrastructure management. Attackers with access to the local area network can perform unauthorized configuration changes that may compromise network security, alter routing tables, modify firewall rules, or disable critical services. The ability to trigger backend diagnostic operations could provide attackers with additional information about the device's internal state and potentially enable further exploitation through information disclosure vulnerabilities. This vulnerability aligns with CWE-284 (Improper Access Control) and represents a classic example of insecure direct object reference where the application fails to verify that the user has proper authorization to access specific resources.
The systemic nature of this issue across the CGI handler chain suggests a broader architectural problem within the device's web interface implementation, indicating that similar vulnerabilities may exist throughout the management interface. This architectural weakness creates a persistent risk profile where multiple attack surfaces can be exploited with a single bypass technique. Organizations should consider implementing network segmentation and access controls to limit local network access to administrative interfaces, while also monitoring for unauthorized configuration changes that might indicate exploitation attempts.
Mitigation strategies should include immediate firmware updates to versions that address the authentication bypass vulnerability, along with network-level restrictions such as firewall rules that limit access to management endpoints to trusted administrative networks only. Network administrators should implement monitoring solutions to detect unusual patterns of access to these endpoints and establish baseline configurations for comparison against potential unauthorized changes. The implementation of multi-factor authentication and secure remote access solutions should also be considered for devices that require external administration access, while regular security assessments should be conducted to identify additional vulnerabilities within the device's management interface and overall network infrastructure.
This vulnerability demonstrates the critical importance of server-side validation in preventing authentication bypass attacks and aligns with ATT&CK technique T1078.004 (Valid Accounts: Cloud Accounts) and T1566.002 (Phishing: Spearphishing Attachment) where attackers might leverage such vulnerabilities to gain unauthorized access to network infrastructure and potentially escalate privileges through additional exploitation techniques. The device's failure to implement proper access controls represents a fundamental security gap that could enable attackers to establish persistent access points within the network infrastructure while maintaining operational capabilities that would be difficult to detect without comprehensive monitoring solutions.