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Dir 816 FirmwareOperating system · Dlink

CVE-2026-4182

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-16
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 weakness has been identified in D-Link DIR-816 1.10CNB05. This impacts an unknown function of the file /goform/form2Wl5RepeaterStep2.cgi of the component goahead. This manipulation of the argument key1/key2/key3/key4/pskValue causes stack-based buffer overflow. Remote exploitation of the attack is possible. The exploit has been made available to the public and could be used for attacks. 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 router's goahead web server component. The form2Wl5RepeaterStep2.cgi handler fails to properly bounds-check the key1/key2/key3/key4/pskValue parameters before copying them to stack buffers, allowing remote attackers to potentially execute arbitrary code with the privileges of the web server.

MitigationReplace the end-of-life D-Link DIR-816 device, as no vendor patch is available. If immediate replacement is not feasible, implement network segmentation to restrict access to the router's web management interface from untrusted networks.

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. Identify the router model
    Access the router's web admin interface or check the device label/metadata to confirm the model is D-Link DIR-816
    Affected if The device is not a D-Link DIR-816 model
  2. Confirm firmware version
    Log into the router's web interface and navigate to Status or System settings to view the firmware version, or use the router's upgrade page to check the current version
    Affected if Firmware version is 1.10CNB05
  3. Verify web server is enabled
    Attempt to access the router's web management interface by entering the router's IP address in a browser (typically 192.168.0.1 or 192.168.1.1)
    Affected if The web interface responds and is accessible
  4. Check network exposure of management interface
    Determine if the router's web interface is accessible from external networks by testing remote IP access or reviewing firewall rules
    Affected if The management web interface is exposed to untrusted networks (not behind a firewall or VPN)
  5. Verify vulnerable CGI handler exists
    Check if the form2Wl5RepeaterStep2.cgi endpoint exists by attempting to access it via HTTP POST to the router's web interface path /form2Wl5RepeaterStep2.cgi
    Affected if The CGI handler responds (even with an error) indicating the vulnerable component is present

The environment is affected if it is a D-Link DIR-816 router running firmware version 1.10CNB05 with its web management interface accessible (especially from untrusted networks), as the vulnerable form2Wl5RepeaterStep2.cgi handler will be present and exploitable.

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 the end-of-life D-Link DIR-816 device, as no vendor patch is available. If immediate replacement is not feasible, implement network segmentation to restrict access to the router's web management interface from untrusted networks.

Recommended fix Moderate confidence
  1. This vulnerability affects D-Link DIR-816 firmware 1.10CNB05, which D-Link has explicitly stated is no longer supported.
  2. Replace the affected D-Link DIR-816 router with a currently supported model from D-Link or another vendor.
  3. If immediate replacement is not possible, disable the router's web management interface from the internet by ensuring remote administration is turned off in the device settings.
  4. Place the affected device behind a properly configured firewall with no exposed web management ports to the internet.
  5. Monitor the network for any suspicious traffic targeting the /goform/form2Wl5RepeaterStep2.cgi endpoint.
  6. Consider deploying an intrusion detection/prevention system (IDS/IPS) to detect and block exploitation attempts targeting this buffer overflow vulnerability.
Caveat The DIR-816 is end-of-life with no firmware updates available from D-Link; replacement with a supported router is the only secure option

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

Fix this in Dir 816 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2026-4182 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

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