CVE-2025-70802 is a vulnerability identified in the Tenda G1V3.1si router firmware version V16.01.7.8. The root cause is a hardcoded password embedded in the /etc_ro/shadow file, which is a critical system file that stores hashed passwords for user accounts. This flaw allows an attacker to bypass authentication mechanisms and log in directly as the root user, granting full administrative privileges. The vulnerability does not require prior authentication or user interaction, but it requires local access to the device, either physically or via a compromised internal network. Once exploited, the attacker gains complete control over the device, enabling them to manipulate configurations, intercept or redirect network traffic, install persistent malware, or launch attacks against other networked systems. The vulnerability is classified under CWE-259 (Use of Hard-coded Password) and has a CVSS v3.1 base score of 8.4, indicating high severity with impacts on confidentiality, integrity, and availability. Although no public exploits have been reported yet, the presence of a hardcoded root password is a critical security weakness that could be leveraged by attackers with access to the device. No official patches or firmware updates have been released at the time of this report, increasing the urgency for affected users to implement compensating controls.

The impact of CVE-2025-70802 is significant for organizations using the affected Tenda G1V3.1si routers with the vulnerable firmware. An attacker gaining root access can fully compromise the device, leading to loss of confidentiality through interception of sensitive data, loss of integrity by altering device configurations or firmware, and loss of availability by disabling or disrupting network services. This can facilitate further attacks such as lateral movement within internal networks, man-in-the-middle attacks, or establishing persistent backdoors. Critical infrastructure, enterprises, and home users relying on these routers for secure network connectivity are at risk. The vulnerability's exploitation could undermine trust in network security and potentially cause operational disruptions or data breaches. Since the vulnerability requires local access, the risk is higher in environments where physical or internal network security is weak or where attackers can gain foothold inside the network perimeter.

1. Restrict physical and local network access to the affected Tenda G1V3.1si routers to trusted personnel only. 2. Monitor device logs and network traffic for signs of unauthorized root logins or suspicious activities. 3. Disable remote management interfaces if not required, to reduce attack surface. 4. Implement network segmentation to isolate vulnerable devices from critical assets. 5. Regularly audit and inventory network devices to identify those running the vulnerable firmware version. 6. Contact Tenda support or monitor official channels for firmware updates or patches addressing this vulnerability and apply them promptly once available. 7. Consider replacing affected devices with models from vendors with stronger security track records if patches are delayed or unavailable. 8. Employ intrusion detection systems (IDS) to detect anomalous behavior indicative of exploitation attempts.