Executive Summary

CVE-2026-2876 is a critical stack-based buffer overflow vulnerability found in the Tenda A18 router, version 15.13.07.13.

The flaw exists in the function parse_macfilter_rule within the /goform/setBlackRule endpoint, specifically due to improper handling of the deviceList argument.

Manipulating the deviceList parameter with crafted input causes a stack-based buffer overflow, which can be exploited remotely without local access or physical interaction.

This vulnerability can lead to denial of service or potentially arbitrary code execution on the device.

Useful 0 Not Useful 0

Impact Analysis

Exploitation of this vulnerability can compromise the confidentiality, integrity, and availability of the affected Tenda A18 router.

An attacker can remotely trigger a denial of service (DoS) or execute arbitrary code, potentially taking control of the device.

This could disrupt network operations, lead to unauthorized access, or cause device malfunction.

Useful 0 Not Useful 0

Compliance Impact

I don't know

Useful 0 Not Useful 0

Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability involves a stack-based buffer overflow triggered by manipulation of the 'deviceList' parameter in the '/goform/setBlackRule' endpoint of the Tenda A18 router firmware version 15.13.07.13."}, {'type': 'paragraph', 'content': "Detection on your network or system would involve monitoring for suspicious or malformed HTTP requests targeting the '/goform/setBlackRule' endpoint, especially those containing unusually long or crafted 'deviceList' parameters."}, {'type': 'paragraph', 'content': 'Since the vulnerability is exploited remotely via HTTP requests, you can use network traffic inspection tools or intrusion detection systems (IDS) to look for such patterns.'}, {'type': 'list_item', 'content': "Use tools like tcpdump or Wireshark to capture HTTP traffic to the router and filter for requests to '/goform/setBlackRule'."}, {'type': 'list_item', 'content': 'Example tcpdump command: tcpdump -i <interface> -A \'tcp port 80 and (((ip dst <router_ip>) and (tcp[32:4] contains "/goform/setBlackRule")))\''}, {'type': 'list_item', 'content': "Use curl or similar HTTP clients to test the endpoint with crafted 'deviceList' parameters to see if the device responds abnormally or crashes."}, {'type': 'list_item', 'content': "Deploy IDS rules that detect unusually long or malformed 'deviceList' parameters in HTTP POST requests to '/goform/setBlackRule'."}] [1, 2, 3]

Useful 0 Not Useful 0

Mitigation Strategies

[{'type': 'paragraph', 'content': 'No known mitigations or patches are currently available for this vulnerability.'}, {'type': 'paragraph', 'content': 'The recommended immediate step is to replace the affected Tenda A18 router (firmware version 15.13.07.13) with an alternative product that is not vulnerable.'}, {'type': 'paragraph', 'content': "Additionally, you should restrict remote access to the router's management interface to trusted networks only, and monitor for any suspicious activity targeting the '/goform/setBlackRule' endpoint."}, {'type': 'paragraph', 'content': 'Implement network-level protections such as firewalls or intrusion prevention systems to block exploit attempts.'}] [1, 3]

Useful 0 Not Useful 0