CVE-2026-4252 in AC8
Summary
by MITRE • 03/16/2026
A vulnerability was identified in Tenda AC8 16.03.50.11. Affected by this issue is the function check_is_ipv6 of the component IPv6 Handler. The manipulation leads to reliance on ip address for authentication. It is possible to initiate the attack remotely. The exploit is publicly available and might be used.
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Analysis
by VulDB Data Team • 03/21/2026
This vulnerability resides in the Tenda AC8 router firmware version 16.03.50.11 where the IPv6 Handler component contains a critical flaw in the check_is_ipv6 function. The issue stems from improper validation of IP address handling during authentication processes, creating a significant security weakness that allows unauthorized access. The vulnerability specifically targets the authentication mechanism that relies on IPv6 address validation, fundamentally undermining the device's security posture. According to CWE-284, this represents an improper access control vulnerability where the system fails to properly verify the authenticity of network connections based on IP address information. The flaw enables attackers to bypass authentication mechanisms by manipulating IPv6 address validation routines, which directly impacts the router's ability to distinguish between legitimate and malicious network traffic.
The technical exploitation of this vulnerability occurs through remote attack vectors, allowing malicious actors to initiate attacks from external networks without requiring physical access to the device. The publicly available exploit demonstrates that threat actors can readily leverage this flaw to gain unauthorized administrative access to the router configuration. This remote exploit capability aligns with ATT&CK technique T1190, which describes the use of remote services to gain initial access to systems. The authentication bypass allows attackers to modify router settings, potentially redirecting traffic, disabling security features, or establishing persistent access points within the network. The vulnerability's impact extends beyond simple unauthorized access as it provides a foundation for more sophisticated attacks including man-in-the-middle operations and network reconnaissance.
The operational impact of this vulnerability poses severe risks to network security infrastructure, particularly in environments where the Tenda AC8 router serves as a gateway device. Organizations relying on this firmware version face potential data breaches, network disruption, and compromised network integrity. The vulnerability's exploitation can lead to complete network takeover, allowing attackers to monitor traffic, modify routing tables, and potentially establish backdoors for future access. Security teams must consider the implications of this flaw in their risk assessments, particularly for critical infrastructure deployments where such devices may be exposed to external networks. The presence of a publicly available exploit accelerates the risk timeline, as organizations cannot assume that attackers will not actively target vulnerable installations. Network segmentation and monitoring become critical defensive measures to detect and mitigate potential exploitation attempts.
Mitigation strategies should prioritize immediate firmware updates from Tenda to address the specific vulnerability in the IPv6 Handler component. Organizations should implement network monitoring to detect anomalous traffic patterns that might indicate exploitation attempts, particularly around IPv6 address validation routines. Network administrators should consider disabling IPv6 functionality on affected devices if not required for operations, reducing the attack surface. Additional defensive measures include implementing strict access control lists, network segmentation, and regular vulnerability assessments to identify similar issues in other network devices. The vulnerability highlights the importance of secure coding practices in network infrastructure devices, particularly in authentication and validation routines. Regular security audits and firmware update policies should be enforced to prevent similar issues in other network equipment, as the flaw represents a fundamental breakdown in authentication security controls that could affect similar router implementations.