CVE-2025-70238: D-Link DIR-513 Buffer Overflow Flaw

CVE-2025-70238 Overview

A stack buffer overflow vulnerability exists in D-Link DIR-513 firmware version 1.10. The vulnerability is triggered through the curTime parameter when processing requests to the goform/formSetWAN_Wizard52 endpoint. This flaw allows remote attackers to cause a denial of service condition by sending specially crafted requests to the affected router without requiring authentication.

Critical Impact

Remote attackers can exploit this vulnerability over the network without authentication to crash the device, causing a denial of service condition that disrupts network connectivity for all connected clients.

Affected Products

• D-Link DIR-513 Hardware
• D-Link DIR-513 Firmware version 1.10
• Devices running affected firmware accessible over the network

Discovery Timeline

• 2026-03-09 - CVE CVE-2025-70238 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2025-70238

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption flaw that occurs when a program writes data beyond the boundary of a fixed-size stack buffer. In the case of CVE-2025-70238, the D-Link DIR-513 router's web management interface fails to properly validate the length of the curTime parameter before copying it to a stack-allocated buffer.

The vulnerability is accessible over the network without requiring any authentication or user interaction, making it particularly dangerous for devices exposed to the internet or untrusted network segments. When exploited, the overflow can corrupt stack memory including the saved return address, leading to a denial of service through application crash.

Root Cause

The root cause is insufficient input validation in the formSetWAN_Wizard52 handler function within the router's web server. When processing the curTime parameter, the firmware copies user-supplied input into a fixed-size stack buffer without checking whether the input length exceeds the buffer capacity. This allows attackers to supply an oversized value that overwrites adjacent stack memory.

Attack Vector

The attack is conducted remotely over the network by sending an HTTP request to the router's web management interface. The attacker targets the goform/formSetWAN_Wizard52 endpoint with a maliciously crafted curTime parameter containing data that exceeds the expected buffer size.

The attack does not require authentication, meaning any attacker with network access to the router's management interface can exploit this vulnerability. When the oversized curTime parameter is processed, the stack buffer overflow corrupts critical stack data, causing the web server process to crash and resulting in a denial of service condition.

For technical details regarding the vulnerability, refer to the GitHub CVE Report.

Detection Methods for CVE-2025-70238

Indicators of Compromise

• Unexpected router reboots or unresponsive web management interface
• HTTP requests to /goform/formSetWAN_Wizard52 with abnormally large curTime parameter values
• Network traffic logs showing repeated POST requests to the WAN wizard configuration endpoint
• Router crash logs indicating memory corruption or segmentation faults in the web server process

Detection Strategies

• Monitor HTTP traffic to the router for requests containing unusually long parameter values in formSetWAN_Wizard52 requests
• Implement network intrusion detection rules to alert on malformed requests targeting D-Link router configuration endpoints
• Deploy network segmentation to restrict access to router management interfaces from untrusted networks
• Configure logging on network devices to capture and analyze traffic patterns targeting router administration paths

Monitoring Recommendations

• Enable comprehensive logging on network firewalls and intrusion detection systems to capture traffic to router management ports
• Monitor router uptime and availability to detect potential denial of service attacks
• Review network access controls to ensure router management interfaces are not exposed to the internet
• Implement automated alerts for unusual traffic patterns targeting IoT and network device management endpoints

How to Mitigate CVE-2025-70238

Immediate Actions Required

• Restrict access to the router's web management interface to trusted administrative networks only
• Disable remote management access if not required for operations
• Implement firewall rules to block external access to the router's configuration endpoints
• Consider replacing end-of-life devices with supported alternatives if patches are unavailable

Patch Information

D-Link has published information regarding this vulnerability. Administrators should consult the D-Link Security Bulletin for the latest firmware updates and security advisories. Additionally, product-specific information is available from the D-Link Product Information page.

Given that the D-Link DIR-513 is an older product, administrators should verify whether firmware updates addressing this vulnerability are available or if the device has reached end-of-life status.

Workarounds

• Disable the web management interface if not needed and use alternative management methods
• Place the router behind a separate firewall that can filter malicious requests
• Use network access control lists (ACLs) to limit which IP addresses can access the management interface
• Monitor for and block requests with oversized parameters targeting configuration endpoints

# Example firewall rule to restrict router management access (iptables)
# Block external access to router management port
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP