CVE-2026-5046 identifies a critical stack-based buffer overflow vulnerability in the Tenda FH1201 router firmware version 1.2.0.14(408). The vulnerability resides in the formWrlExtraSet function of the /goform/WrlExtraSet component, which handles parameter input. Specifically, improper handling of the GO argument allows an attacker to overflow the stack buffer, potentially overwriting return addresses or other control data. This flaw can be exploited remotely over the network without requiring authentication or user interaction, making it highly accessible to attackers. Successful exploitation can lead to arbitrary code execution with elevated privileges, enabling attackers to take full control of the device, disrupt network operations, or pivot into internal networks. The CVSS v4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with ease of exploitation. Although no active exploits have been detected in the wild, a proof-of-concept exploit is publicly available, increasing the likelihood of exploitation attempts. The vulnerability affects a specific firmware version, so devices running this version or earlier are at risk. The lack of an official patch at the time of publication necessitates immediate mitigation efforts by users and administrators.

The impact of CVE-2026-5046 is significant for organizations relying on Tenda FH1201 routers, particularly those running firmware version 1.2.0.14(408). Exploitation can lead to complete compromise of the router, allowing attackers to execute arbitrary code with high privileges. This can result in interception or manipulation of network traffic, disruption of network availability, and unauthorized access to internal networks. For enterprises, this could mean data breaches, loss of sensitive information, and interruption of critical services. In environments where these routers serve as gateways or are part of critical infrastructure, the risk escalates to operational and reputational damage. The remote and unauthenticated nature of the exploit increases the attack surface, making widespread automated attacks feasible once exploit code is weaponized. The absence of known active exploits currently provides a window for remediation, but the published exploit code elevates the urgency for mitigation.

1. Immediate firmware upgrade: Check for and apply any official patches or firmware updates from Tenda addressing this vulnerability. If no patch is available, contact Tenda support for guidance. 2. Network segmentation: Isolate affected routers from critical network segments to limit potential lateral movement in case of compromise. 3. Access control: Restrict remote management interfaces and disable unnecessary services to reduce exposure to external attackers. 4. Input filtering: Deploy network-level intrusion prevention systems (IPS) or web application firewalls (WAF) capable of detecting and blocking malformed requests targeting /goform/WrlExtraSet endpoints. 5. Monitoring and logging: Enable detailed logging on routers and network devices to detect anomalous activities indicative of exploitation attempts. 6. Incident response readiness: Prepare to respond to potential compromises by maintaining backups, and having procedures to reset or replace affected devices. 7. Vendor engagement: Encourage Tenda to release timely patches and advisories, and subscribe to vulnerability notification services to stay informed.