CVE-2026-7854 in DI-8100
Summary
by MITRE • 05/05/2026
A security vulnerability has been detected in D-Link DI-8100 16.07.26A1. Affected by this vulnerability is the function url_rule_asp of the file /url_rule.asp of the component POST Parameter Handler. Such manipulation leads to buffer overflow. It is possible to launch the attack remotely. The exploit has been disclosed publicly and may be used.
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Analysis
by VulDB Data Team • 05/09/2026
This vulnerability affects the D-Link DI-8100 router model with firmware version 16.07.26A1, specifically targeting the url_rule_asp function within the /url_rule.asp file of the POST Parameter Handler component. The flaw represents a classic buffer overflow vulnerability that occurs when user-supplied input is processed without proper bounds checking, allowing an attacker to overwrite adjacent memory locations in the application's execution space. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions where insufficient boundary checking allows attackers to overwrite adjacent memory, potentially leading to arbitrary code execution. The vulnerability is particularly concerning because it can be exploited remotely, eliminating the need for physical access to the device or local network presence, which aligns with the ATT&CK technique T1190 for exploitation of remote services.
The buffer overflow vulnerability in the url_rule_asp function demonstrates a critical weakness in input validation and memory management practices within the router's web interface handling component. When the system processes POST parameters through the url_rule.asp file, it fails to properly validate the length of input data before copying it into fixed-size buffers, creating an exploitable condition that allows attackers to inject malicious data beyond the allocated memory boundaries. This flaw enables attackers to potentially overwrite return addresses, function pointers, or other critical program variables, which could result in complete system compromise and unauthorized access to the network. The public disclosure of the exploit means that threat actors can readily leverage this vulnerability without requiring advanced technical skills or custom exploit development.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it could enable attackers to gain complete control over the router's functionality and potentially use it as a pivot point for broader network attacks. An attacker who successfully exploits this vulnerability could modify firewall rules, redirect traffic through malicious proxies, change administrator credentials, or even install persistent backdoors on the device. The router's role as a network gateway makes it an attractive target for attackers seeking to establish persistent access to internal networks, as demonstrated by ATT&CK technique T1071.004 for application layer protocol usage in command and control communications. Furthermore, the vulnerability could be exploited in conjunction with other network reconnaissance activities to map network topology and identify additional vulnerable devices within the same network segment.
Mitigation strategies should prioritize immediate firmware updates from D-Link to address the buffer overflow condition in the url_rule.asp component, which would involve implementing proper input validation and bounds checking mechanisms to prevent the overflow scenario. Network administrators should also implement additional security controls including disabling unnecessary web management interfaces, restricting access to the router's administrative functions through firewall rules, and monitoring for suspicious network traffic patterns that might indicate exploitation attempts. The vulnerability's remote exploitability necessitates network-level protections such as intrusion detection systems that can identify and block malicious POST requests targeting the vulnerable url_rule.asp endpoint. Organizations should also consider implementing network segmentation strategies to limit the potential impact of a successful compromise and establish robust patch management procedures to ensure timely deployment of security updates. Security monitoring should include regular vulnerability scanning of network devices to identify similar buffer overflow conditions in other components and prevent exploitation of related vulnerabilities.