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The vulnerability CVE-2025-46108 resides in the `formTcpipSetup` function of the D-Link DIR-513 router running firmware version A1FW110. The device utilizes the `boa` web server to handle HTTP requests. During initialization, various callback functions are registered to process specific form requests. When a POST request is sent to the `/goform/formTcpipSetup` endpoint, the corresponding `formTcpipSetup` callback is triggered. This function is responsible for processing parameters related to TCP/IP setup, such as IP addresses, subnet masks, and gateways. The vulnerability is specifically a classic stack-based buffer overflow caused by the improper use of the `sprintf` function . The `formTcpipSetup` function extracts a user-supplied parameter (likely related to network configuration, similar to the `curTime` parameter in other DIR-513 vulnerabilities) and copies it into a fixed-size stack buffer using `sprintf` without validating the length of the input . Because there are no bounds checks, an attacker can send an extremely long string for this parameter. This oversized data overflows the buffer, overwriting adjacent memory on the stack, including the return address of the function. By carefully crafting this payload, an attacker can hijack the program’s execution flow. Since the web server often runs with root privileges, successful exploitation allows the attacker to redirect execution to malicious shellcode, ultimately granting them full remote control over the device. This can lead to a complete system compromise, allowing the attacker to add the device to a botnet, monitor network traffic, or pivot to internal network assets. The attack can be launched remotely over the network without requiring any authentication, making it extremely dangerous for any exposed or internally accessible vulnerable devices .
dailycve form:
Platform: D-Link DIR-513
Version: A1FW110
Vulnerability : Buffer Overflow
Severity: Critical
Date: 03/04/2026
Prediction: Unlikely (EOL)
What Undercode Say:
Analytics:
The exploitability of this CVE is high due to the lack of required privileges and user interaction . Analysis of similar D-Link vulnerabilities shows that the `boa` web server is a frequent target, with buffer overflows often found in functions that handle `goform` parameters without proper bounds checking . The device is likely End-of-Life (EOL), meaning no official patch will be released, leaving users responsible for mitigation.
How Exploit:
Step 1: Identify the target and confirm the vulnerable endpoint
Use a tool like curl to interact with the router's web interface
Example: Attempt to cause a Denial of Service (DoS) to confirm the overflow
TARGET_IP="192.168.0.1"
VULN_ENDPOINT="/goform/formTcpipSetup"
Step 2: Create a long string to overflow the buffer.
Generate a pattern of 1000 characters to send as a parameter.
The exact vulnerable parameter name is not specified in the CVE description,
but based on similar vulnerabilities, it might be a parameter like 'curTime' or an IP field.
We will use a generic parameter name 'long_param' for demonstration.
Create a malicious payload
PAYLOAD=$(python3 -c "print('A' 1000)")
Step 3: Send the exploit using curl to trigger the overflow
This command sends a POST request with the long payload as a parameter.
If successful, this may cause the router's web service to crash (DoS).
curl -X POST http://$TARGET_IP/$VULN_ENDPOINT \
-d "long_param=$PAYLOAD"
Step 4: For a full Remote Code Execution (RCE), the payload would need to be crafted.
This involves:
1. Finding the exact offset to overwrite the return address.
2. Creating a ROP chain to bypass any security mitigations (if present, unlikely on such an old device).
3. Including shellcode (e.g., a bind shell or reverse shell).
Example of a bind shell shellcode generation (msfvenom):
msfvenom -p linux/mipsbe/shell_bind_tcp LPORT=4444 -f python
Note: DIR-513 likely uses a MIPS architecture.
Protection from this CVE:
As this is likely an End-of-Life (EOL) device, D-Link will not provide a security patch. The only effective protection is to isolate or retire the device immediately. Users should replace the DIR-513 with a supported model. If replacement is not immediately possible, strict network segmentation is required: place the router behind a firewall with strict access control lists (ACLs) to block all inbound traffic to ports 80/443 (web interface) from the WAN side. Disable remote management entirely. If the device is only needed for local use, ensure the management interface is not exposed to the internet.
Impact:
Successful exploitation results in complete system compromise. An unauthenticated attacker can gain root shell access to the device . This allows for the exfiltration of network credentials, man-in-the-middle attacks on local traffic, and the installation of malware to recruit the router into a botnet for large-scale DDoS attacks. The integrity of network communication passing through the device is completely lost.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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