CVE-2025-3786: Critical Buffer Overflow Vulnerability in Tenda AC15

Overview

A severe vulnerability has been identified in Tenda AC15, a widely used WiFi router, that could potentially lead to system compromise or data leakage. This vulnerability, designated as CVE-2025-3786, affects versions up to 15.03.05.19 and has been classified as critical. It lies within the function fromSetWirelessRepeat of the file /goform/WifiExtraSet, where a manipulation of the ‘mac’ argument allows for a buffer overflow. This vulnerability matters because it can be exploited remotely, posing a significant risk to all systems and networks using the affected Tenda AC15 routers.

Vulnerability Summary

CVE ID: CVE-2025-3786
Severity: Critical, CVSS Score 8.8
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Tenda AC15 | Up to 15.03.05.19

How the Exploit Works

The exploit works by manipulating the ‘mac’ argument in the fromSetWirelessRepeat function. By passing an oversized input to this argument, an attacker can trigger a buffer overflow, causing the system to overwrite memory that was not allocated for this purpose. This can lead to unpredictable system behavior, including crashes, data corruption, and code execution. In this case, an attacker could potentially gain control over the system or access sensitive information.

Conceptual Example Code

Here’s a conceptual example of how an attacker might trigger this vulnerability:

POST /goform/WifiExtraSet HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
mac=00:00:00:00:00:00%00...[repeat until buffer overflow]

In this example, the MAC address argument is filled with a long string of null bytes, triggering a buffer overflow.
For network administrators and security professionals, it’s crucial to apply the vendor-supplied patch immediately. As a temporary measure, a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can be used to mitigate the risk.