Overview
The cybersecurity community has recently identified a critical vulnerability in Tenda AC8 16.03.34.06, a popular router firmware. This vulnerability, designated as CVE-2025-11120, is a buffer overflow vulnerability that exists in the formSetServerConfig function of the SetServerConfig file. The severity of this vulnerability lies in the fact that it can be exploited remotely, enabling potential system compromise and data leakage. Given that the exploit has been made publicly available, it poses a significant risk to any system utilizing the affected version of Tenda AC8.
Vulnerability Summary
CVE ID: CVE-2025-11120
Severity: Critical (8.8 CVSS Score)
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: System compromise or data leakage
Affected Products
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Product | Affected Versions
Tenda AC8 | 16.03.34.06
How the Exploit Works
The exploit takes advantage of a buffer overflow vulnerability present in the formSetServerConfig function. By sending specially crafted packets to this function, an attacker can overflow the buffer, thereby leading to unexpected behaviors such as crashes, incorrect processing of data, or even the execution of arbitrary code. In the case of CVE-2025-11120, the latter scenario is possible, leading to potential system compromise or data leakage.
Conceptual Example Code
Below is a conceptual example of how the vulnerability might be exploited. The attacker sends a POST request with a malicious payload designed to overflow the buffer.
POST /goform/SetServerConfig HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "formSetServerConfig": "A"*1024 }In this example, the string “A”*1024 represents a large amount of data that is intended to overflow the buffer.
Mitigation Guidance
The best mitigation strategy for this vulnerability is to apply the patch provided by the vendor. In the event the patch cannot be immediately applied, a temporary mitigation option would be to use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and block attempts to exploit this vulnerability. However, these are only temporary solutions, and updating to the patched version as soon as possible is strongly advised.
