D-Link DI-8100 Buffer Overflow Vulnerability

A critical buffer overflow vulnerability, tracked as CVE-2026-7247, has been discovered in D-Link DI-8100 router firmware version 16.07.26A1. The vulnerability resides within the file_exten_asp function of the file_exten.asp component, specifically the File Extension Handler. Successful exploitation could allow an attacker to execute arbitrary code on the device. The vulnerability is triggered by manipulating the Name argument, leading to a buffer overflow. Publicly available exploits exist, increasing the risk of widespread exploitation. Given the potential for remote exploitation and the existence of public exploits, organizations using the affected D-Link DI-8100 router should take immediate action.

Attack Chain

1. The attacker identifies a vulnerable D-Link DI-8100 router running firmware 16.07.26A1.
2. The attacker crafts a malicious HTTP request targeting the file_exten.asp endpoint.
3. The crafted request includes a Name argument with a payload exceeding the buffer size in the file_exten_asp function.
4. The router processes the malicious request, triggering the buffer overflow when handling the oversized Name argument.
5. The buffer overflow overwrites adjacent memory regions, potentially including return addresses or function pointers.
6. The attacker redirects execution flow to injected shellcode or existing code gadgets (ROP).
7. The injected code executes with the privileges of the web server process.
8. The attacker gains remote code execution on the D-Link DI-8100 router, potentially allowing for device takeover or network compromise.

Impact

Successful exploitation of this vulnerability allows for remote code execution on the D-Link DI-8100 router. An attacker could gain complete control of the device, potentially using it as a pivot point for further attacks within the network. This could lead to data exfiltration, denial of service, or the installation of malicious firmware. Given the existence of public exploits, a wide range of actors could leverage this vulnerability, impacting potentially thousands of devices.

Recommendation

• Monitor web server logs for suspicious requests targeting file_exten.asp with abnormally long Name parameters to detect potential exploitation attempts. (Log Source: webserver, Rule: Suspicious File Extension ASP Request).
• Implement rate limiting on web requests to the D-Link DI-8100's management interface to mitigate potential brute-force exploitation attempts. (Log Source: firewall, Affected Product: DI-8100 16.07.26A1)
• Apply any available patches or firmware updates released by D-Link to address CVE-2026-7247. (Affected Product: DI-8100 16.07.26A1)