CVE-2026-4555 identifies a critical stack-based buffer overflow vulnerability in the D-Link DIR-513 router firmware version 1.10, specifically within the formEasySetTimezone function of the boa embedded web server component. The vulnerability arises from improper validation and handling of the curTime parameter passed to the /goform/formEasySetTimezone endpoint. An attacker can craft a malicious request that overflows the stack buffer, potentially overwriting the return address or other control data, enabling arbitrary code execution on the device. This can lead to full compromise of the router, including the ability to execute commands with elevated privileges. The vulnerability is remotely exploitable without requiring authentication or user interaction, making it highly accessible to attackers scanning for vulnerable devices on the internet. Although the product is no longer supported and no official patches exist, a public exploit has been released, increasing the likelihood of exploitation in the wild. The boa web server is a lightweight HTTP server commonly used in embedded devices, and this flaw highlights the risks of legacy firmware with unpatched vulnerabilities. The CVSS v4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with ease of exploitation. The scope is limited to the DIR-513 version 1.10 firmware, but affected devices remain at risk until replaced or mitigated.

The impact of CVE-2026-4555 is significant for organizations and individuals relying on the D-Link DIR-513 router version 1.10. Successful exploitation can lead to complete compromise of the router, allowing attackers to execute arbitrary code with elevated privileges. This can result in interception or manipulation of network traffic, disruption of network availability, and potential pivoting to internal networks for further attacks. Confidential information passing through the router may be exposed or altered, undermining data integrity and privacy. Since the device is no longer supported, no official patches are available, leaving vulnerable devices exposed indefinitely. The public availability of an exploit increases the risk of automated attacks and widespread compromise. Organizations using these routers in critical environments face risks of service disruption, data breaches, and unauthorized network access. The vulnerability also poses risks to home users who may be unaware of the threat or unable to upgrade their hardware. Overall, the vulnerability threatens the confidentiality, integrity, and availability of affected networks and devices.

Given the lack of official patches for the unsupported D-Link DIR-513 firmware, the most effective mitigation is to replace the affected routers with newer, supported models that receive regular security updates. If immediate replacement is not feasible, organizations should isolate these devices from untrusted networks, especially the internet, by placing them behind firewalls or network segmentation to limit exposure. Disabling remote management features and restricting access to the router’s web interface to trusted internal IP addresses can reduce attack surface. Network monitoring should be enhanced to detect unusual traffic patterns or exploitation attempts targeting the /goform/formEasySetTimezone endpoint. Employing intrusion detection or prevention systems with signatures for this exploit can help identify and block attacks. Regularly auditing network devices for outdated firmware and maintaining an inventory of legacy hardware will aid in proactive risk management. Educating users about the risks of unsupported devices and encouraging timely hardware upgrades is also critical. Finally, consider deploying network-level protections such as VPNs or encrypted tunnels to safeguard sensitive communications from compromised routers.