Dnr 202l FirmwareOperating system · Dlink

CVE-2026-4194

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-16
Fix available
A fix is available. Upgrade to after 2026-02-05 or later.
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 detected in D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-1100-4, DNS-1200-05 and DNS-1550-04 up to 20260205. The impacted element is the function cgi_set_wto of the file /cgi-bin/system_mgr.cgi. Performing a manipulation results in improper access controls. Remote exploitation of the attack is possible. The exploit is now public and may be used.

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 · moderate confidence

Improper access control vulnerability in D-Link NAS and camera devices allows remote unauthenticated attackers to access the cgi_set_wto function in /cgi_bin/system_mgr.cgi. The lack of authentication/authorization checks on this CGI endpoint enables attackers to potentially execute arbitrary commands or access sensitive system management functions without credentials.

MitigationIsolate affected devices from untrusted networks immediately. Apply vendor firmware updates if available, or consider replacing end-of-life devices. If the web interface is not required, disable it.

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
Dnr 202l FirmwareOperating system
Affected:<= 2026-02-05
Dnr 326 FirmwareOperating system
Affected:<= 2026-02-05
Dns 1100 4 FirmwareOperating system
Affected:<= 2026-02-05
Dns 120 FirmwareOperating system
Affected:<= 2026-02-05
Dns 1200 05 FirmwareOperating system
Affected:<= 2026-02-05
Dns 1550 04 FirmwareOperating system
Affected:<= 2026-02-05
Dns 315l FirmwareOperating system
Affected:<= 2026-02-05
Dns 320 FirmwareOperating system
Affected:<= 2026-02-05

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 device model
    Access the device web interface or check the device label/documentation to confirm the exact model number matches one of: Dnr 202l, Dnr 326, Dns 1100 4, Dns 120, Dns 1200 05, Dns 1550 04, Dns 315l, or Dns 320
    Affected if The device model is any of the listed affected models
  2. Check the firmware version
    Log into the device web interface (if accessible) and navigate to the System or Status section to view the firmware build date or version. Compare it to the 2026-02-05 threshold
    Affected if The firmware version date is on or before 2026-02-05
  3. Verify web interface accessibility
    Attempt to access the device web interface over HTTP/HTTPS from the network. Confirm the /cgi_bin/ path is reachable
    Affected if The web interface and cgi_bin directory are accessible from the network
  4. Confirm the cgi_set_wto function exists
    If the endpoint responds, examine if the response indicates the cgi_set_wto function is present and callable without authorization
    Affected if The function responds or executes without authentication being required

A user is affected if they have any of the listed D-Link device models running firmware dated 2026-02-05 or earlier, with the web interface accessible on the network and the system_mgr.cgi endpoint responding without authentication.

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.

From vendor data
Upgrade available Upgrade to a release after 2026-02-05
Interim mitigation

Isolate affected devices from untrusted networks immediately. Apply vendor firmware updates if available, or consider replacing end-of-life devices. If the web interface is not required, disable it.

Fix this in Dnr 202l Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,680
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Scan for this in your stack

Free · runs locally
dbcve dependency scanner

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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-2026-4194 in production — separate from our analysis above.

No notes yet

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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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data