Dir 816 Firmware CVE-2025-5630

Despite the 9.8 CVSS score indicating critical severity, real-world risk assessment reveals significant exploitability factors: (1) Attack Vector: Network - unauthenticated remote exploitation is possible without authentication; (2) Attack Complexity: Low - no special conditions required; (3) Privileges Required: None - no user interaction or authentication needed; (4) User Interaction: None - fully automated exploitation feasible; (5) Scope: Unchanged - impact limited to affected router; (6) Technical Impact: All CIA compromised (Confidentiality, Integrity, Availability). The disclosure of working exploit code elevates practical risk substantially. However, mitigating factors include: (a) Limited target scope - only DIR-816 v1.10CNB05 affected; (b) Outdated hardware - primarily in legacy deployments; (c) Requires network access to router management interface; (d) Many users may have replaced this EOL hardware. EPSS scoring would likely be HIGH (0.75+) given public POC availability and low exploitation complexity. The combination of public exploits, high CVSS, low complexity, and unauthenticated access makes this a legitimate priority for affected organizations despite vendor abandonment.

An attacker conducts network reconnaissance and identifies a D-Link DIR-816 router with firmware 1.10CNB05 on a target network (via default web interface port 80/443 or fingerprinting). The attacker crafts an HTTP request to http://[router-ip]/goform/form2lansetup.cgi with an oversized 'ip' parameter value exceeding the buffer size (e.g., 1000+ characters of 'A's or shellcode). This malformed request causes a stack buffer overflow, overwriting the return pointer on the stack. The attacker can leverage this to execute arbitrary code with router privileges (typically root), enabling: complete device compromise, credential harvesting from configuration, installation of persistent backdoors, DNS hijacking, traffic interception, or launching attacks against internal network resources. No authentication is required, and the attack requires only network connectivity to the router's web interface. Public POC code reduces barrier to exploitation significantly. Attack execution takes seconds and can be automated for widespread scanning and exploitation of vulnerable device populations.