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Dir 816 FirmwareOperating system · Dlink

CVE-2025-5623

CRITICAL · 9.8 CVSS v3.1 Published 2025-06-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability was found in D-Link DIR-816 1.10CNB05. It has been classified as critical. This affects the function qosClassifier of the file /goform/qosClassifier. The manipulation of the argument dip_address/sip_address leads to stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Stack-based buffer overflow in D-Link DIR-816 1.10CNB05 firmware in the qosClassifier function allows remote attackers to execute arbitrary code via manipulated dip_address/sip_address arguments.

MitigationReplace unsupported D-Link DIR-816 hardware with a currently-supported device; if immediate replacement is not feasible, disable WAN access and isolate the device on a restricted network segment.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Dir 816 FirmwareOperating system
Affected:= 1.10cnb05

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm device model
    Inspect the router label or log into the web interface to verify the device is a D-Link DIR-816
    Affected if Device is not a D-Link DIR-816 then it is not affected by this specific CVE
  2. Check firmware version
    Log into the router web interface (typically 192.168.0.1) and navigate to the Status or System Information page to view the firmware version, or check via telnet/SSH if enabled
    Affected if Firmware version is exactly 1.10cnb05 - this is the only affected version listed for this CVE
  3. Verify qosClassifier accessibility
    Check if QoS settings are accessible in the router web interface under Advanced or Bandwidth Management settings; the qosClassifier function handles QoS classification using dip_address/sip_address
    Affected if QoS feature is enabled and accessible, making the vulnerable code path reachable
  4. Check WAN management exposure
    In the router web interface, go to Advanced > Remote Management and verify if WAN-side management or HTTP/HTTPS management from WAN is enabled
    Affected if WAN-facing management interfaces are enabled, allowing remote attackers to reach the vulnerable function over the internet

Your device is affected if it is a D-Link DIR-816 running firmware version 1.10cnb05 with the QoS classifier feature accessible and potentially WAN management exposed.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Replace unsupported D-Link DIR-816 hardware with a currently-supported device; if immediate replacement is not feasible, disable WAN access and isolate the device on a restricted network segment.

Recommended fix High confidence

Replace with a currently supported D-Link model (e.g., DIR-2660, DIR-1960, or DIR-3060)

  1. This vulnerability affects D-Link DIR-816 firmware 1.10CNB05, which D-Link has explicitly stated is no longer supported.
  2. Replace the end-of-life DIR-816 with a currently supported D-Link router model that receives security updates.
  3. If replacement is not immediately possible, implement network segmentation to isolate the vulnerable device from untrusted networks.
  4. Configure firewall rules to restrict access to the router's management interface to only trusted IP addresses.
  5. Monitor D-Link's product support pages for any potential out-of-cycle security advisories, though none are currently promised for this EOL product.
Caveat Replacing the router will require reconfiguration of network settings and re-establishing any port forwarding or QoS rules

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Dir 816 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-5623 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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