CVE-2025-70247: D-Link DIR-513 Buffer Overflow Flaw

CVE-2025-70247 Overview

A stack buffer overflow vulnerability has been identified in D-Link DIR-513 firmware version 1.10. The vulnerability exists in the goform/formSetWizard1 endpoint and can be exploited through the curTime parameter. This flaw allows attackers to send specially crafted requests that overflow the stack buffer, potentially leading to denial of service conditions on affected devices.

Critical Impact

Remote attackers can exploit this stack buffer overflow vulnerability without authentication to cause denial of service on vulnerable D-Link DIR-513 routers, disrupting network connectivity for all connected devices.

Affected Products

• D-Link DIR-513 Firmware version 1.10
• D-Link DIR-513 Hardware

Discovery Timeline

• 2026-03-10 - CVE-2025-70247 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2025-70247

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption flaw that occurs when data is written beyond the allocated boundary of a stack buffer. The vulnerability resides in the web management interface of the D-Link DIR-513 router, specifically within the goform/formSetWizard1 form handler responsible for device setup wizard functionality.

The attack can be initiated remotely over the network without requiring any prior authentication or user interaction. When exploited, the vulnerability primarily impacts the availability of the device, causing service disruption. The router's firmware fails to properly validate the length of the curTime parameter before copying it into a fixed-size stack buffer.

Root Cause

The root cause of CVE-2025-70247 is improper input validation in the form handler code. The curTime parameter received from HTTP requests is processed without adequate bounds checking before being stored in a stack-allocated buffer. When an attacker provides input exceeding the expected buffer size, the data overflows into adjacent stack memory, corrupting return addresses and other critical stack data.

Attack Vector

The attack vector is network-based, targeting the router's web management interface. An attacker can exploit this vulnerability by:

1. Sending a malicious HTTP POST request to the goform/formSetWizard1 endpoint
2. Including an oversized curTime parameter value designed to overflow the target buffer
3. The overflow corrupts stack memory, leading to service disruption

The vulnerability can be exploited remotely without authentication. The curTime parameter, intended to handle time-related configuration data during the setup wizard, becomes the attack surface when supplied with excessive input data. For detailed technical analysis, refer to the GitHub CVEreport Repository.

Detection Methods for CVE-2025-70247

Indicators of Compromise

• Unexpected router reboots or service unavailability without administrative action
• Large HTTP POST requests to goform/formSetWizard1 with abnormally long curTime parameter values
• Web interface becoming unresponsive following suspicious network activity
• Error logs indicating memory corruption or segmentation faults in the web server process

Detection Strategies

• Monitor network traffic for HTTP requests targeting goform/formSetWizard1 with unusually large payloads
• Implement intrusion detection rules to flag HTTP POST requests with curTime parameters exceeding normal length thresholds
• Deploy network-based anomaly detection to identify buffer overflow attack patterns against embedded devices
• Review router access logs for repeated requests to the wizard endpoint from unexpected sources

Monitoring Recommendations

• Enable logging on network firewalls to capture traffic to router management interfaces
• Configure alerts for sudden loss of connectivity to D-Link DIR-513 devices
• Implement network segmentation to restrict management interface access to trusted administrative networks
• Regularly audit device uptime and responsiveness to detect potential exploitation attempts

How to Mitigate CVE-2025-70247

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management access if not required for operations
• Place affected D-Link DIR-513 devices behind a firewall that filters malicious requests
• Consider replacing end-of-life devices with actively supported alternatives

Patch Information

D-Link has published information regarding this vulnerability. Organizations should check the D-Link Security Bulletin for official guidance on patches or firmware updates. Additionally, product-specific support information can be found at the D-Link Product Support Page.

Given that the DIR-513 is an older product model, users should verify whether D-Link will provide a security update or if the device has reached end-of-life status, in which case device replacement is recommended.

Workarounds

• Configure firewall rules to block external access to the router's management interface on port 80/443
• Use network access control lists (ACLs) to limit which IP addresses can reach the management interface
• Disable the setup wizard functionality if the device is already configured and the feature is not needed
• Implement a VPN requirement for any remote administration access to the network

# Configuration example - Restrict management interface access via iptables on upstream firewall
# Block external access to router management interface
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 443 -j DROP

# Allow only trusted admin subnet
iptables -I FORWARD -s 192.168.10.0/24 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT