CVE-2026-5024 Overview
A stack-based buffer overflow vulnerability has been identified in D-Link DIR-513 firmware version 1.10. This vulnerability exists in the formSetEmail function within the /goform/formSetEmail endpoint, where improper handling of the curTime argument allows attackers to overflow the stack buffer. The vulnerability is remotely exploitable, enabling attackers to potentially execute arbitrary code or cause denial of service on affected devices.
Critical Impact
This vulnerability affects end-of-life D-Link DIR-513 routers that are no longer receiving security updates from the manufacturer, leaving devices permanently vulnerable to exploitation.
Affected Products
- D-Link DIR-513 Firmware version 1.10
- D-Link DIR-513 Hardware (all revisions running affected firmware)
Discovery Timeline
- 2026-03-29 - CVE-2026-5024 published to NVD
- 2026-03-30 - Last updated in NVD database
Technical Details for CVE-2026-5024
Vulnerability Analysis
This vulnerability is classified as a stack-based buffer overflow (CWE-787: Out-of-bounds Write, CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the formSetEmail function, which processes HTTP requests sent to the /goform/formSetEmail endpoint on the router's web management interface.
When the function receives the curTime parameter, it fails to properly validate the length of the input before copying it into a fixed-size stack buffer. This lack of bounds checking allows an attacker to supply an oversized value that exceeds the buffer's allocated space, corrupting adjacent stack memory including potentially the function's return address.
Root Cause
The root cause of this vulnerability is insufficient input validation in the formSetEmail function. The function accepts user-supplied data through the curTime argument without verifying that the input length is within acceptable bounds before performing memory operations. This is a classic example of unsafe string handling in embedded firmware, where resource constraints often lead to the omission of proper bounds checking.
Attack Vector
The attack vector is network-based, requiring no user interaction. An authenticated attacker with access to the router's web management interface can craft a malicious HTTP request to the /goform/formSetEmail endpoint containing an oversized curTime parameter value. The exploitation mechanism involves:
- Sending a crafted HTTP POST request to /goform/formSetEmail
- Including an excessively long curTime parameter that exceeds the expected buffer size
- Overwriting stack memory to potentially hijack program execution flow
- Achieving remote code execution or causing a denial of service condition
Technical details and proof-of-concept information are available in the GitHub PoC Repository and the VulDB #353908 entry.
Detection Methods for CVE-2026-5024
Indicators of Compromise
- Unusual HTTP POST requests to /goform/formSetEmail with abnormally long curTime parameter values
- Router crashes or unexpected reboots following web management interface access
- Anomalous network traffic patterns originating from the router's management interface
- Unexpected modifications to router configuration or firmware
Detection Strategies
- Monitor web server logs for HTTP requests to /goform/formSetEmail containing unusually large parameter values
- Deploy network intrusion detection rules to identify buffer overflow exploitation attempts targeting D-Link routers
- Implement traffic analysis for suspicious POST request patterns to router management endpoints
- Use SentinelOne Singularity to detect anomalous behavior and exploitation attempts on network devices
Monitoring Recommendations
- Enable logging on all network boundary devices and monitor for exploitation attempts
- Implement network segmentation to isolate vulnerable end-of-life devices from critical infrastructure
- Deploy honeypots configured as vulnerable D-Link routers to detect active exploitation campaigns
- Regularly audit network inventory for unsupported devices like the DIR-513
How to Mitigate CVE-2026-5024
Immediate Actions Required
- Identify all D-Link DIR-513 devices in your network environment and document their locations
- Restrict access to the router's web management interface to trusted networks only
- Consider replacing affected devices with currently supported hardware
- Implement network segmentation to limit potential attack surface
Patch Information
No official patch is available for this vulnerability. D-Link has discontinued support for the DIR-513 router, meaning this device will not receive security updates. According to the D-Link Main Site, users of end-of-life products are advised to upgrade to newer, supported hardware.
For additional vulnerability information, refer to:
Workarounds
- Disable remote management and restrict web interface access to local network connections only
- Implement strict firewall rules to block external access to the router's management ports
- Use a VPN for remote administration instead of exposing the management interface directly
- Replace the DIR-513 with a currently supported router model that receives security updates
# Example iptables rules to restrict management interface access
# Block external access to router management ports
iptables -A INPUT -p tcp --dport 80 -i eth0 -j DROP
iptables -A INPUT -p tcp --dport 443 -i eth0 -j DROP
# Allow management access only from trusted internal network
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
