Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-3970 is a stack-based buffer overflow vulnerability found in the Tenda i3 router, version 1.0.0.6(2204). It exists in the function formwrlSSIDget, which is accessed via the /goform/wifiSSIDget HTTP endpoint.'}, {'type': 'paragraph', 'content': 'The vulnerability arises from improper handling and insufficient validation of the length of the "index" parameter in HTTP POST requests. An attacker can send a crafted POST request with an excessively long string in the "index" field, causing a stack-based buffer overflow.'}, {'type': 'paragraph', 'content': 'This overflow can overwrite local variables or function parameters on the stack, potentially leading to denial of service or arbitrary code execution on the affected device.'}, {'type': 'paragraph', 'content': 'The exploit is publicly available, making it easier for attackers to leverage this flaw remotely without authentication.'}] [1, 2, 3]

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Impact Analysis

This vulnerability can impact you by compromising the confidentiality, integrity, and availability of the affected Tenda i3 router.

• Denial of Service (DoS): The device can be crashed or rendered unusable by exploiting the buffer overflow.
• Arbitrary Code Execution: An attacker may execute malicious code remotely on the device, potentially gaining control over it.
• Remote Exploitation: The attack can be launched remotely without requiring authentication, increasing the risk.

Because the exploit is publicly available, the risk of exploitation is higher, and no known mitigations exist other than replacing the affected product.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by sending a crafted HTTP POST request to the /goform/wifiSSIDget endpoint of the Tenda i3 router, specifically manipulating the "index" parameter with an excessively long string to trigger the buffer overflow.'}, {'type': 'paragraph', 'content': 'A proof of concept involves sending a POST request with a large payload of repeated characters (e.g., \'a\') in the "index" field.'}, {'type': 'paragraph', 'content': 'An example command using curl to test for the vulnerability could be:'}, {'type': 'list_item', 'content': 'curl -X POST http://[router_ip]/goform/wifiSSIDget -d "index=$(python3 -c \'print("a"*1000)\')"'}, {'type': 'paragraph', 'content': 'Replace [router_ip] with the IP address of the target device. If the device crashes, behaves unexpectedly, or returns an error, it may be vulnerable.'}] [1, 3]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'No known countermeasures or mitigations have been identified for this vulnerability.'}, {'type': 'paragraph', 'content': 'The recommended immediate step is to replace the affected Tenda i3 router (version 1.0.0.6(2204)) with an alternative device that is not vulnerable.'}, {'type': 'paragraph', 'content': "Additionally, restricting network access to the router's management interface and monitoring for suspicious POST requests to /goform/wifiSSIDget may help reduce risk until replacement."}] [2]

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