CVE-2025-70241: Dlink Dir-513 Buffer Overflow Vulnerability

CVE-2025-70241 Overview

A critical stack buffer overflow vulnerability has been identified in D-Link DIR-513 router firmware version 1.10. The vulnerability exists in the goform/formSetWANType_Wizard5 endpoint and can be triggered via a maliciously crafted curTime parameter. This flaw allows unauthenticated remote attackers to potentially execute arbitrary code or cause a denial of service on affected devices.

Critical Impact

This stack buffer overflow vulnerability allows network-based attackers to compromise D-Link DIR-513 routers without authentication, potentially leading to complete device takeover, network traffic interception, or use of the device in botnet operations.

Affected Products

• D-Link DIR-513 Firmware version 1.10
• D-Link DIR-513 hardware devices
• D-Link DIR-513 series routers running vulnerable firmware

Discovery Timeline

• 2026-03-03 - CVE-2025-70241 published to NVD
• 2026-03-04 - Last updated in NVD database

Technical Details for CVE-2025-70241

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), which occurs when the affected software writes data past the end of an allocated buffer. In the context of the D-Link DIR-513 router, the vulnerability manifests in the web management interface's WAN configuration wizard functionality.

The goform/formSetWANType_Wizard5 endpoint fails to properly validate the length of user-supplied input in the curTime parameter before copying it to a fixed-size stack buffer. When an attacker supplies an oversized value, the excess data overwrites adjacent stack memory, potentially including saved return addresses and other critical control data.

Due to the network-accessible nature of this endpoint and the lack of authentication requirements, attackers can exploit this vulnerability remotely. The impact includes potential arbitrary code execution with the privileges of the web server process (typically root on embedded devices), complete device compromise, and denial of service conditions.

Root Cause

The root cause of CVE-2025-70241 is insufficient input validation in the firmware's web server component. The curTime parameter handler copies user-supplied data into a stack-allocated buffer without first verifying that the input length does not exceed the buffer's capacity. This is a classic buffer overflow scenario common in embedded device firmware where secure coding practices may not be rigorously enforced.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can craft a malicious HTTP POST request to the goform/formSetWANType_Wizard5 endpoint with an oversized curTime parameter value. When the vulnerable firmware processes this request, the buffer overflow occurs, allowing the attacker to:

1. Overwrite stack canaries (if present)
2. Corrupt saved frame pointers
3. Hijack the return address to redirect execution flow
4. Potentially execute shellcode or ROP chains to achieve code execution

The vulnerability is exploitable from any network segment that can reach the router's web management interface, which may include the LAN, guest networks, or in some configurations, the WAN interface.

The vulnerability occurs when processing the curTime parameter in the WAN configuration wizard endpoint. The firmware fails to validate the length of this parameter before copying it to a fixed-size stack buffer, leading to a classic stack-based buffer overflow condition. For detailed technical analysis, refer to the GitHub CVE Report.

Detection Methods for CVE-2025-70241

Indicators of Compromise

• Unusual HTTP POST requests to goform/formSetWANType_Wizard5 with abnormally large curTime parameter values
• Router crashes, unexpected reboots, or unresponsive web management interface
• Unexpected outbound connections from the router to unknown IP addresses
• Modified firmware files or configuration changes not made by administrators

Detection Strategies

• Deploy network intrusion detection rules to identify oversized POST requests targeting D-Link web management endpoints
• Monitor for HTTP requests containing the pattern /goform/formSetWANType_Wizard5 with payloads exceeding normal parameter lengths
• Implement web application firewall rules to block requests with suspiciously long parameter values to router management interfaces
• Enable and review router system logs for segmentation faults or crash events

Monitoring Recommendations

• Continuously monitor network traffic to and from D-Link routers for anomalous patterns
• Establish baseline behavior for router web interface access and alert on deviations
• Deploy SentinelOne Singularity for IoT to gain visibility into device behavior and detect exploitation attempts
• Consider network segmentation to limit exposure of router management interfaces

How to Mitigate CVE-2025-70241

Immediate Actions Required

• Check the D-Link Security Bulletin for firmware updates addressing this vulnerability
• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management features if not required for operations
• Consider placing affected devices behind additional network security controls until patched

Patch Information

D-Link users should monitor the D-Link Security Bulletin for official firmware updates that address CVE-2025-70241. Additionally, product-specific information can be found on the D-Link Product Information page. Apply any available security patches immediately following vendor instructions.

Workarounds

• Disable access to the web management interface from untrusted networks
• Implement firewall rules to block external access to the router's management ports (typically HTTP/80 and HTTPS/443)
• Use a VPN for remote administration instead of exposing the management interface directly
• Consider replacing end-of-life devices that may not receive security updates

# Example firewall rule to restrict management access (iptables)
# Allow management access only from trusted admin network
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP