Overview
An alarming cybersecurity vulnerability, classified as critical, has been identified in D-Link DIR-632 FW103B08. This flaw is coded as CVE-2025-6121 and affects the function get_pure_content of the HTTP POST request handler. This vulnerability is severe as it can potentially lead to a system compromise or data leakage, jeopardizing the privacy and security of users and businesses alike. Given the fact that the vulnerability affects products no longer supported by the maintainer, this matter is further complicated, necessitating immediate and careful attention.
Vulnerability Summary
CVE ID: CVE-2025-6121
Severity: Critical, with a CVSS score of 9.8
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: A successful exploitation of this vulnerability could lead to a complete system compromise or potential data leakage.
Affected Products
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Product | Affected Versions
D-Link DIR-632 | FW103B08
How the Exploit Works
The vulnerability resides in the HTTP POST request handler of D-Link DIR-632 FW103B08. More specifically, the function get_pure_content is susceptible to manipulation via the Content-Length argument, resulting in a stack-based buffer overflow. This condition is often exploited to execute arbitrary code or cause a denial of service. The attack can be performed remotely, making it a crucial threat to any systems running the vulnerable software version.
Conceptual Example Code
Here is a conceptual example of how the vulnerability might be exploited. This example uses an HTTP POST request with manipulated Content-Length:
POST /get_pure_content HTTP/1.1
Host: vulnerable-device.example.com
Content-Type: application/x-www-form-urlencoded
Content-Length: [manipulated value]
data=[malicious payload]In the above example, the Content-Length value is manipulated to overflow the buffer in the get_pure_content function, potentially allowing for arbitrary code execution.
Mitigation Guidance
As the products affected by this vulnerability are no longer supported by the maintainer, the primary recommendation is to replace these devices with a newer, supported model where possible. If this is not immediately achievable, a temporary mitigation strategy would be to apply a vendor patch or employ a Web Application Firewall (WAF) or Intrusion Detection System (IDS). These protective measures can help detect and prevent attacks leveraging this vulnerability until a more permanent solution can be implemented.