CVE-2026-6013 Overview
A buffer overflow vulnerability has been identified in D-Link DIR-513 routers running firmware version 1.10. This vulnerability affects the formSetRoute function within the /goform/formSetRoute POST Request Handler component. Improper handling of the curTime argument allows remote attackers to trigger a buffer overflow condition, potentially leading to arbitrary code execution or denial of service on affected devices.
Critical Impact
Remote attackers can exploit this buffer overflow vulnerability to potentially execute arbitrary code or crash the device. This vulnerability affects end-of-life products that are no longer receiving security updates from D-Link.
Affected Products
- D-Link DIR-513 firmware version 1.10
- Products in end-of-life status without vendor support
Discovery Timeline
- April 10, 2026 - CVE-2026-6013 published to NVD
- April 13, 2026 - Last updated in NVD database
Technical Details for CVE-2026-6013
Vulnerability Analysis
This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The formSetRoute function in the D-Link DIR-513 router firmware fails to properly validate the length of the curTime argument before copying it into a fixed-size buffer. When processing maliciously crafted POST requests to /goform/formSetRoute, the function does not perform adequate boundary checks, allowing an attacker to write beyond the allocated buffer space.
The exploit for this vulnerability has been publicly disclosed, increasing the risk of exploitation in the wild. Since this vulnerability affects a product that is no longer supported by D-Link, no official patches will be released, making affected devices permanently vulnerable.
Root Cause
The root cause is improper input validation in the formSetRoute function when handling the curTime parameter. The firmware code allocates a fixed-size buffer for the curTime input but does not verify that incoming data conforms to expected length constraints before memory copy operations. This classic buffer overflow pattern allows attackers to overwrite adjacent memory regions, potentially including return addresses or function pointers.
Attack Vector
The attack can be performed remotely over the network by sending specially crafted HTTP POST requests to the /goform/formSetRoute endpoint. An attacker with low-level privileges (authenticated access to the router's web interface) can manipulate the curTime parameter to include oversized data, triggering the buffer overflow.
The attack does not require user interaction beyond initial network access. Since this is a router vulnerability, successful exploitation could allow an attacker to:
- Gain control of network traffic routing
- Execute arbitrary code with router firmware privileges
- Cause denial of service by crashing the device
- Pivot to attack other devices on the local network
Technical details and proof-of-concept information are available in the VulDB vulnerability entry and the Notion research document.
Detection Methods for CVE-2026-6013
Indicators of Compromise
- Unusual HTTP POST requests to /goform/formSetRoute with abnormally large curTime parameter values
- Router crashes or unexpected reboots without administrative action
- Modified routing tables or network configuration changes
- Suspicious outbound network connections from the router
Detection Strategies
- Monitor HTTP traffic to router management interfaces for POST requests to /goform/formSetRoute containing oversized parameters
- Implement network intrusion detection rules to identify buffer overflow exploitation attempts targeting D-Link devices
- Deploy web application firewall rules to block requests with excessively long parameter values to goform endpoints
- Review router logs for repeated failed authentication attempts followed by successful exploitation
Monitoring Recommendations
- Enable logging on network firewalls for traffic destined to router management ports (typically 80, 443, 8080)
- Set up alerts for configuration changes on network devices, particularly routing table modifications
- Monitor for firmware integrity using file hash comparisons where supported
- Implement network segmentation to limit exposure of vulnerable devices
How to Mitigate CVE-2026-6013
Immediate Actions Required
- Disable remote management access to the D-Link DIR-513 router immediately
- Restrict access to the router's web management interface to trusted IP addresses only
- Place the affected device behind a firewall that blocks external access to management interfaces
- Plan for immediate device replacement as this product is end-of-life
Patch Information
No official patch is available for this vulnerability. D-Link has discontinued support for the DIR-513 router, and no security updates will be released. Organizations using this device must implement compensating controls or replace the affected hardware with a currently supported product.
For more information, visit the D-Link Official Website to identify supported replacement devices.
Workarounds
- Completely disable remote management features on the router
- Implement strict network access controls to limit management interface access to local administration only
- Deploy a separate firewall or access control list in front of the vulnerable device
- Replace the end-of-life D-Link DIR-513 with a currently supported router model
# Example firewall rule to block external access to router management
# Adjust interface and IP addresses for your environment
iptables -A INPUT -i eth0 -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -i eth0 -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
