D-Link DI-8100 CVE-2026-7855

Exploitation requires valid authentication credentials (CVSS PR:L - low-privilege user access) to the D-Link DI-8100's web administration interface. Attacker must have network connectivity to the router's HTTP/HTTPS management ports (typically TCP 80/443), which are exploitable if exposed to untrusted networks or if the attacker has compromised an internal network host with management access. The vulnerable endpoint /tggl.asp must be accessible to the authenticated user session - if D-Link implements role-based access controls that restrict certain users from accessing tggl.asp functionality, those users may not be able to exploit this vulnerability. Attack complexity is low (AC:L) with no additional attack complexity factors (AT:N), indicating exploitation does not require winning race conditions, gathering additional information, or special environmental configurations beyond standard router deployment. No user interaction required (UI:N), meaning exploitation is fully automated once credentials are obtained. Limiting factors: authentication barrier prevents anonymous remote exploitation; organizations using strong password policies, multi-factor authentication on management VPNs, or IP whitelisting significantly reduce exploitation risk; devices not exposing management interfaces to the internet or untrusted networks are protected by network segmentation.

This vulnerability presents moderate-to-high real-world risk for organizations using D-Link DI-8100 routers. The CVSS v4.0 score of 7.4 reflects network-accessible exploitation (AV:N) with low complexity (AC:L) but requires low-privilege authentication (PR:L). The Exploit Maturity indicator (E:P) confirms public proof-of-concept availability, corroborated by the GitHub repository containing detailed exploitation steps. However, the authentication requirement significantly constrains the attack surface compared to unauthenticated RCE - attackers need valid router credentials first, typically obtained through credential stuffing, phishing, or default password exploitation. EPSS data is not provided, but the combination of public exploit code and network accessibility suggests non-zero exploitation probability within exposed or weakly-configured devices. The vulnerability is NOT currently listed in CISA KEV, indicating no confirmed widespread active exploitation campaigns at time of analysis. Primary risk factors: publicly documented exploit lowers technical barriers; network vector enables remote compromise; high confidentiality/integrity/availability impact (VC:H/VI:H/VA:H) permits complete device takeover. Mitigating factors: authentication requirement limits opportunistic scanning attacks; DI-8100 is a business router with presumably lower deployment density than consumer models; scope unchanged (SC:N) means exploitation doesn't breach security boundaries beyond the vulnerable component.

An attacker who has obtained valid credentials to a D-Link DI-8100 router (through credential stuffing, default password exploitation, or social engineering) authenticates to the web administration interface over the network. They craft a malicious HTTP POST request to /tggl.asp with an oversized Name parameter containing shellcode or return-oriented programming gadgets designed to overflow the buffer in the tggl_asp function. The overflow overwrites return addresses or function pointers, redirecting execution to attacker-controlled code. The attacker achieves arbitrary code execution with router privileges, enabling firmware replacement, traffic interception, network pivot operations, or permanent device compromise. The publicly available GitHub exploit code provides ready-made attack tooling requiring minimal technical adaptation.