Overview
A critical vulnerability has been discovered in D-Link DIR-825 (Version 2.03), a widely used wireless router. This vulnerability, identified as CVE-2025-6291, resides in the HTTP POST request handler of the device. It is especially concerning given the device’s widespread usage and the potential for remote exploitation. The issue lies within the do_file() function, which when manipulated, leads to a stack-based buffer overflow. This type of vulnerability can potentially lead to a complete system compromise or leak sensitive data, making it a significant concern for the cybersecurity community.
Vulnerability Summary
CVE ID: CVE-2025-6291
Severity: Critical (CVSS: 8.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
D-Link DIR-825 | 2.03
How the Exploit Works
The exploit takes advantage of the vulnerability in the HTTP POST request handler’s do_file() function. By sending a specially crafted HTTP POST request, an attacker can cause a stack-based buffer overflow. This overflow happens when the system writes more data to a buffer than it can hold. The excess data can corrupt data, crash the system, or allow the execution of malicious code, potentially leading to full system control.
Conceptual Example Code
Here’s a conceptual example of how an attacker might exploit this vulnerability. This is not actual exploit code, but a simplification to illustrate the general idea:
POST /target_file HTTP/1.1
Host: vulnerable_router.example.com
Content-Type: application/x-www-form-urlencoded
file_name=<overly_long_string>&file_content=<malicious_code>In this example, `
Mitigation Guidance
Users are advised to apply the vendor-supplied patch to address this vulnerability as soon as possible. If a patch cannot be applied immediately, implementing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigation. However, these measures are not a substitute for patching the system. Please note that this vulnerability only affects products that are no longer supported by the maintainer, so upgrading to a supported product version is also advised.