CVE-2025-13445 is a critical stack-based buffer overflow vulnerability identified in the Tenda AC21 router firmware version 16.03.08.16. The vulnerability resides in the /goform/SetIpMacBind endpoint, which is part of the router's web management interface. By manipulating the argument list sent to this endpoint, an attacker can cause a stack overflow due to insufficient bounds checking on input parameters. This overflow can overwrite the stack frame, potentially allowing an attacker to execute arbitrary code with the privileges of the web server process, which typically runs with elevated rights on the device. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, making it highly dangerous. The CVSS v4.0 score of 8.7 reflects the ease of exploitation (network vector, low complexity), lack of required privileges or user interaction, and the high impact on confidentiality, integrity, and availability. While no confirmed exploits in the wild have been reported, the availability of exploit code increases the likelihood of future attacks. The flaw could be leveraged to gain persistent control over the router, intercept or modify network traffic, or launch further attacks within the local network or against connected devices. No official patches or mitigation instructions have been published yet, increasing the urgency for defensive measures.

The impact of CVE-2025-13445 is significant for organizations using Tenda AC21 routers. Successful exploitation allows attackers to execute arbitrary code remotely with elevated privileges, potentially leading to full device compromise. This can result in unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of network services, and use of the compromised router as a foothold for lateral movement or launching attacks on other systems. The confidentiality of network traffic and stored configuration data is at risk, as is the integrity of network operations. Availability may be affected if attackers disrupt router functionality or cause crashes. Given the router’s role as a network gateway, the vulnerability poses a critical risk to enterprise, SMB, and home networks relying on this device. The lack of authentication requirement and remote exploitability further amplify the threat, making it accessible to a wide range of attackers including opportunistic threat actors and advanced persistent threats.

1. Immediate mitigation should include isolating affected Tenda AC21 devices from untrusted networks, especially the internet, to reduce exposure. 2. Network administrators should implement strict firewall rules to block access to the router’s web management interface (port 80/443 or custom ports) from untrusted sources. 3. Monitor network traffic for unusual activity or signs of exploitation attempts targeting the /goform/SetIpMacBind endpoint. 4. Disable remote management features on the router if not strictly necessary. 5. Regularly back up router configurations and maintain an inventory of affected devices to prioritize patching once an official firmware update is released. 6. Engage with Tenda support or vendor channels to obtain or request security patches or firmware updates addressing this vulnerability. 7. Consider deploying network segmentation to limit the impact of a compromised router on critical systems. 8. Employ intrusion detection/prevention systems (IDS/IPS) with signatures tuned to detect exploitation attempts of this vulnerability. 9. Educate network users and administrators about the risks and signs of router compromise. 10. As a longer-term measure, evaluate alternative network hardware with stronger security postures if timely patching is not feasible.