Overview
CVE-2025-65220 describes a buffer overflow vulnerability present in Tenda AC21 routers, specifically version V16.03.08.16. This vulnerability allows a remote attacker to potentially execute arbitrary code on the router, leading to a compromise of the device and the network it serves. The vulnerability lies in the handling of the `list` parameter within the `/goform/SetVirtualServerCfg` endpoint.
Technical Details
The vulnerability is a buffer overflow that occurs when the router processes the `list` parameter in the `/goform/SetVirtualServerCfg` endpoint. An attacker can send a specially crafted request with an overly long `list` parameter value. Because the router software doesn’t properly validate the length of this input, it overflows the buffer allocated for it, potentially overwriting adjacent memory locations. This allows for the possibility of injecting and executing malicious code on the router.
The vulnerable software version is Tenda AC21 V16.03.08.16.
CVSS Analysis
Currently, a CVSS score for CVE-2025-65220 is not available (N/A). This could be due to the vulnerability being newly discovered or the analysis still being in progress. However, given the nature of buffer overflow vulnerabilities, it is likely to receive a high CVSS score upon completion of a formal risk assessment. A successful exploit could lead to complete compromise of the device.
Possible Impact
The exploitation of CVE-2025-65220 can have severe consequences:
- Remote Code Execution (RCE): An attacker can execute arbitrary code on the router, gaining complete control over the device.
- Data Exfiltration: The attacker can steal sensitive data transmitted through the network.
- Denial of Service (DoS): The attacker can crash the router, disrupting network connectivity.
- Malware Propagation: The compromised router can be used as a launching pad for attacks on other devices on the network.
- Network Pivoting: The attacker can use the router as a gateway to access other devices on the network, even those behind a firewall.
Mitigation or Patch Steps
Currently, a patch or firmware update to address this vulnerability is not yet available. The following steps are recommended to mitigate the risk:
- Monitor Tenda’s website for firmware updates: Regularly check the official Tenda website for any announcements regarding a patch for CVE-2025-65220.
- Disable Remote Administration: If possible, disable remote administration access to the router to reduce the attack surface.
- Use a Strong Password: Ensure that you have a strong and unique password for the router’s web interface.
- Network Segmentation: Segment your network to limit the impact of a potential compromise.
- Monitor Network Traffic: Monitor your network traffic for any suspicious activity.
- Consider Alternative Router: If security is a top concern, consider replacing the Tenda AC21 with a more secure router from a reputable vendor.
