Overview
We’re diving into a critical cybersecurity vulnerability that was discovered in the Tenda CH22 1.0.0.1. This vulnerability, identified as CVE-2025-5685, affects the function formNatlimit of the file /goform/Natlimit and can lead to a stack-based buffer overflow. The criticality of this vulnerability lies in its potential for remote exploitation, which could lead to system compromise and data leakage. In this post, we’ll explore the technical details of this vulnerability, its potential impact, and how to prevent it.
Vulnerability Summary
CVE ID: CVE-2025-5685
Severity: Critical, Score 8.8
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
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Product | Affected Versions
Tenda CH22 | 1.0.0.1
How the Exploit Works
The vulnerability resides in the formNatlimit function of the /goform/Natlimit file. A flaw in the code allows for the manipulation of the ‘page’ argument, resulting in a stack-based buffer overflow. This overflow can then be exploited to execute arbitrary code on the system. The exploit can be initiated remotely without any user interaction or privileges, making the attack particularly insidious and difficult to detect.
Conceptual Example Code
Here’s a conceptual example of how the vulnerability might be exploited through a malicious HTTP request:
POST /goform/Natlimit HTTP/1.1
Host: vulnerable-device-ip
Content-Type: application/x-www-form-urlencoded
page=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...[CONTINUED]In this example, the ‘page’ argument is filled with a long string of ‘A’s to trigger the buffer overflow. In a real-world attack, the attacker would replace this string with malicious code designed to compromise the system.
Impact
A successful exploit of CVE-2025-5685 can lead to total system compromise. This means that an attacker could potentially gain control over the system, modify system settings, or even exfiltrate sensitive data. Given that the vulnerability can be exploited remotely, the potential impact is far-reaching and could affect any system that hasn’t been patched.
Mitigation
The mitigation for this vulnerability is to apply the vendor’s patch. If a patch is not yet available or cannot be applied immediately, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigation until the patch can be applied. Regularly updating and patching systems is an essential part of maintaining a strong security posture and defending against potential attacks.