D-Link DI-8100 CVE-2026-7248

No special conditions-remote unauthenticated exploitation against default configurations of D-Link DI-8100 firmware 16.07.26A1. The attack requires only that the web management interface (tgfile.htm CGI endpoint) be network-accessible to the attacker. While best practice dictates disabling WAN-side management access, many SMB deployments leave this enabled for remote administration. The CVSS vector (AV:N/AC:L/PR:N/UI:N) confirms no authentication, user interaction, or complex configuration is required. The primary limiting factor is network reachability: devices with management interfaces restricted to internal networks or protected by firewall rules blocking external access to management ports (80/443) are not exploitable from the internet, though still vulnerable to insider threats or attackers who have already compromised the internal network.

Real-world risk is CRITICAL for internet-exposed DI-8100 devices. The CVSS 8.9 score accurately reflects severity: network-accessible (AV:N), no authentication required (PR:N), no user interaction needed (UI:N), and high impact across confidentiality, integrity, and availability (VC:H/VI:H/VA:H). The CVSS 4.0 'E:P' (Proof-of-concept) confirms public exploit availability, corroborated by the GitHub repository reference containing detailed exploitation steps. This combination-unauthenticated remote attack, low complexity, public exploit code, and critical infrastructure target (business router)-makes this an immediate priority. The vulnerability enables full device compromise, potentially allowing attackers to intercept traffic, pivot into internal networks, or use the router as a botnet node. D-Link's history of end-of-life support creates additional risk: verify if DI-8100 is still receiving security updates. If EOL, no patch may ever be released, requiring device replacement.

An attacker scans the internet for D-Link DI-8100 routers with exposed web management interfaces (typically TCP 80/443). Upon identifying a target running firmware 16.07.26A1, they craft an HTTP request to tgfile.htm with an oversized 'fn' parameter containing shellcode. The buffer overflow overwrites return addresses on the stack, redirecting execution to attacker-controlled code running with root privileges. The attacker establishes persistent backdoor access, exfiltrates VPN credentials, and pivots into the corporate network behind the router. Public exploit code at https://github.com/draw-ctf/report/blob/main/DI-8100/DI-8100_tgfile_htm_overflow.md provides implementation details, making exploitation straightforward even for moderately skilled attackers.