Critical D-Link Router Flaws Allow Remote Code Execution by Attackers

D-Link has declared its DIR-816 wireless router end-of-life (EOL) following the discovery of six critical security vulnerabilities, urging immediate replacement of all hardware revisions and firmware versions globally.

Published on June 26, 2025, the advisory confirms no future patches will be released for these flaws, which include multiple stack-based buffer overflows and OS command injections rated up to CVSS 9.8/CRITICAL1.

Attackers could exploit these remotely without authentication to execute arbitrary code or commands.

Technical Vulnerability Breakdown

The vulnerabilities primarily affect router management interfaces:

• CVE-2025-5622: Stack overflow in /goform/wirelessApcli_5g via apcli_mode_5g parameters1
• CVE-2025-5623/CVE-2025-5624: Dual flaws in /goform/qosClassifier allowing overflow through dip_address/sip_address1
• CVE-2025-5630: Buffer overflow in /goform/form2lansetup.cgi via IP argument1
• CVE-2025-5620/CVE-2025-5621: OS command injections in /goform/setipsec_config (via localIP/remoteIP) and /goform/qosClassifier1

All exploits enable unauthenticated remote code execution (RCE) with root privileges. CVSS v3.1 vectors confirm network-based attacks requiring no user interaction (AV:N/AC:L/PR:N/UI:N)1.

Mandatory Mitigation Steps

With the DIR-816 entering EOL status on November 10, 2023, D-Link mandates:

1. Immediate retirement of all DIR-816 units1
2. Transition to supported router models with active security updates
3. Comprehensive configuration backups before decommissioning
4. Regional support contact for migration guidance

The manufacturer explicitly states that no firmware patches will be developed for these vulnerabilities, leaving active devices permanently exposed.

Critical Security Implications

Continued use constitutes severe risk:

• Exploits can compromise entire networks via unpatched RCE flaws
• EOL status voids all technical support and security updates
• Temporary precautions (password rotation, WPA3 encryption) offer limited protection if replacement is delayed

D-Link emphasizes that industry standards prohibit security maintenance for EOL products, making replacement the only viable solution.

Consumers should prioritize migrating to currently supported router series with active vulnerability management programs.

This security emergency highlights the critical importance of proactive device lifecycle management.

With all DIR-816 variants now confirmed vulnerable and unpatchable, immediate decommissioning remains the sole responsible action for network operators.

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