CVE-2025-70227: D-Link DIR-513 Buffer Overflow Vulnerability

CVE-2025-70227 Overview

A stack buffer overflow vulnerability has been identified in D-Link DIR-513 firmware version 1.10. The vulnerability exists in the goform/formLanguageChange endpoint, where improper handling of the nextPage parameter allows attackers to trigger a stack-based buffer overflow condition. This firmware vulnerability affects the router's web management interface and can be exploited remotely over the network without authentication.

Critical Impact

Remote attackers can exploit this stack buffer overflow to cause denial of service conditions on affected D-Link DIR-513 routers, potentially disrupting network connectivity for all connected devices.

Affected Products

• D-Link DIR-513 Firmware version 1.10
• D-Link DIR-513 Hardware
• dlink dir-513_firmware

Discovery Timeline

• 2026-03-10 - CVE-2025-70227 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2025-70227

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption issue that occurs when data written to a buffer on the stack exceeds its allocated size. In the context of the D-Link DIR-513, the vulnerable code path exists within the web server component that handles language change requests through the goform/formLanguageChange endpoint.

When a malicious request is sent with an oversized nextPage parameter value, the firmware fails to properly validate the input length before copying it to a fixed-size stack buffer. This overflow condition can corrupt adjacent stack memory, including return addresses and saved registers, leading to unpredictable behavior and service disruption.

Root Cause

The root cause of this vulnerability stems from insufficient input validation in the firmware's web interface handler. The nextPage parameter is processed without adequate bounds checking, allowing an attacker to supply input that exceeds the expected buffer size. This is a common issue in embedded device firmware where memory-constrained environments lead developers to use fixed-size buffers without implementing proper length restrictions on user-controlled input.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker with network access to the router's management interface can craft malicious HTTP requests targeting the goform/formLanguageChange endpoint. The exploit leverages the nextPage parameter to inject oversized data that overflows the stack buffer.

The vulnerability mechanism involves sending a crafted HTTP POST request to the goform/formLanguageChange endpoint with a nextPage parameter containing data exceeding the buffer's allocated size. This causes the stack buffer to overflow, corrupting adjacent memory regions and potentially crashing the web service or the entire device. For detailed technical analysis, refer to the GitHub CVE Report.

Detection Methods for CVE-2025-70227

Indicators of Compromise

• Unexpected router reboots or management interface unavailability
• Anomalous HTTP POST requests to /goform/formLanguageChange with unusually large nextPage parameter values
• Network traffic patterns showing repeated requests to the language change endpoint
• Web server crash logs indicating memory corruption or segmentation faults

Detection Strategies

• Monitor HTTP traffic to D-Link router management interfaces for requests to goform/formLanguageChange with abnormally long parameters
• Implement intrusion detection rules to alert on buffer overflow patterns targeting embedded device web interfaces
• Deploy network-based anomaly detection to identify exploit attempts against IoT and router firmware
• Review router logs for repeated crashes or service restarts that may indicate exploitation attempts

Monitoring Recommendations

• Enable logging on network segments containing vulnerable D-Link devices
• Configure alerts for any access attempts to router management interfaces from untrusted networks
• Monitor for firmware crash patterns that could indicate active exploitation
• Implement network segmentation to isolate IoT and router management interfaces from general network traffic

How to Mitigate CVE-2025-70227

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management if not required for operations
• Implement network segmentation to prevent untrusted hosts from accessing the router's administrative interface
• Monitor the D-Link Security Bulletin for firmware updates addressing this vulnerability

Patch Information

At the time of publication, users should consult the D-Link Security Bulletin for official patch availability and updated firmware releases. Check the D-Link Product Support Page for the latest firmware version for the DIR-513 router.

Workarounds

• Configure firewall rules to block external access to the router's management interface on ports 80 and 443
• Use a separate management VLAN for router administration that is isolated from user traffic
• Disable the web management interface entirely if CLI or other management methods are available
• Consider replacing end-of-life devices if vendor patches are not forthcoming

# 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 management access only from trusted admin workstation
iptables -I FORWARD -s 192.168.1.100 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT