CVE-2025-70234: D-Link DIR-513 Buffer Overflow Vulnerability

CVE-2025-70234 Overview

A stack buffer overflow vulnerability has been identified in D-Link DIR-513 v1.10 routers. The vulnerability exists in the goform/formSetQoS endpoint and can be triggered through the curTime parameter. This memory corruption flaw allows remote attackers to potentially execute arbitrary code or cause denial of service conditions on affected devices without requiring authentication.

Critical Impact

Remote attackers can exploit this stack buffer overflow vulnerability to potentially achieve code execution on affected D-Link DIR-513 routers, compromising network security and enabling further attacks on connected devices.

Affected Products

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

Discovery Timeline

• 2026-03-03 - CVE-2025-70234 published to NVD
• 2026-03-04 - Last updated in NVD database

Technical Details for CVE-2025-70234

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), specifically manifesting as a stack buffer overflow condition. The flaw occurs when the goform/formSetQoS endpoint processes user-supplied input through the curTime parameter without proper bounds checking. When an attacker sends a specially crafted request with an oversized value for this parameter, the application writes data beyond the allocated stack buffer boundaries.

The vulnerability is remotely exploitable over the network without requiring authentication or user interaction. Successful exploitation could allow an attacker to overwrite critical stack data including return addresses, potentially leading to arbitrary code execution with the privileges of the web service process running on the router.

Root Cause

The root cause of this vulnerability stems from insufficient input validation in the firmware's web interface handler. The curTime parameter processing routine allocates a fixed-size buffer on the stack but fails to verify that incoming data does not exceed this allocation. This allows attackers to overflow the buffer and corrupt adjacent memory regions, including function return pointers stored on the stack.

Attack Vector

The attack can be executed remotely over the network by sending malicious HTTP requests to the vulnerable goform/formSetQoS endpoint. The attacker crafts a request containing an oversized curTime parameter value designed to overflow the stack buffer.

The exploitation flow involves:

1. Identifying an exposed D-Link DIR-513 router running vulnerable firmware version 1.10
2. Sending an HTTP POST request to the /goform/formSetQoS endpoint
3. Including an oversized curTime parameter to trigger the buffer overflow
4. Overwriting stack memory to potentially redirect execution flow

For detailed technical analysis of this vulnerability, refer to the GitHub CVE Report Repository.

Detection Methods for CVE-2025-70234

Indicators of Compromise

• Unusual or malformed HTTP POST requests targeting /goform/formSetQoS with abnormally long curTime parameter values
• Unexpected router reboots or service crashes indicating potential exploitation attempts
• Anomalous network traffic patterns originating from the router's management interface
• Web service process crashes or memory-related errors in device logs

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests to goform/formSetQoS with oversized parameter values
• Monitor router syslog for repeated crashes or memory corruption indicators
• Implement web application firewall rules to block requests with excessively long curTime parameters
• Use network traffic analysis to detect potential exploitation payloads targeting embedded device web interfaces

Monitoring Recommendations

• Enable logging on the router's web management interface if supported
• Monitor network traffic for suspicious POST requests to D-Link router administration endpoints
• Set up alerts for router availability to detect potential denial of service conditions
• Implement network segmentation to isolate IoT and router management interfaces from general network traffic

How to Mitigate CVE-2025-70234

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Disable remote management features if not required
• Implement firewall rules to block external access to the router's administration ports
• Consider network segmentation to limit exposure of the vulnerable device

Patch Information

Check the D-Link Security Bulletin for official security updates and firmware releases addressing this vulnerability. Visit the D-Link Product Technical Support page for device-specific firmware updates.

Given that the D-Link DIR-513 may be an end-of-life product, organizations should evaluate whether continued use is advisable or if replacement with a supported device is warranted.

Workarounds

• Restrict administrative interface access to specific trusted IP addresses using access control lists
• Place the router behind a properly configured firewall that blocks external access to management interfaces
• Disable the web-based administration interface if command-line management is available and sufficient
• Monitor the device for unusual behavior and consider replacing with a currently supported router model

# Example: Restrict management interface access via upstream firewall
# Block external access to router management ports
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP

# Allow management access only from specific trusted admin IP
iptables -I FORWARD -s <trusted_admin_ip> -d <router_ip> -p tcp --dport 80 -j ACCEPT