CVE-2025-4356: Critical Buffer Overflow Vulnerability in Tenda DAP-1520

Overview

Cybersecurity vulnerabilities are a constant threat in today’s interconnected world, and the recent discovery of the CVE-2025-4356 vulnerability highlights this fact. This critical security vulnerability, which has been discovered in Tenda DAP-1520 1.10B04_BETA02, affects the Authentication Handler’s function, potentially leading to severe consequences like system compromise or data leakage. This vulnerability is particularly concerning as it can be exploited remotely and has already been disclosed to the public, increasing the risk of misuse by malicious actors.

Vulnerability Summary

CVE ID: CVE-2025-4356
Severity: Critical (8.8 CVSS Severity Score)
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Tenda DAP-1520 | 1.10B04_BETA02

How the Exploit Works

The exploit targets the `mod_graph_auth_uri_handler` function of the `/storage` file in the Tenda DAP-1520’s software. This function is responsible for handling authentication requests, but a flaw in its design allows for a stack-based buffer overflow. In layman’s terms, this means that an attacker can overflow the buffer with excess data, causing the system to write into adjacent memory spaces. This can lead to arbitrary code execution, which allows the attacker to gain unauthorized access to the system or leak sensitive data.

Conceptual Example Code

Below is a conceptual example of how the vulnerability might be exploited. This is a illustrative HTTP request that includes a malicious payload designed to overflow the buffer.

POST /storage/mod_graph_auth_uri_handler HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "auth_request": "A".repeat(2048) }

In this example, the `”A”.repeat(2048)` is a string that is long enough to overflow the buffer in the `mod_graph_auth_uri_handler` function, leading to the potential for arbitrary code execution.

Mitigation Guidance

While the best way to address this vulnerability is to apply the patch provided by the vendor, in the interim, using Web Application Firewalls (WAF) or Intrusion Detection Systems (IDS) can provide temporary mitigation. These systems can potentially block or detect the abnormal behavior associated with the exploitation of this vulnerability. However, it should be emphasized that these are temporary measures, and updating the affected software is the only surefire way to prevent exploitation of this vulnerability.