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Dns 1550 04 FirmwareOperating system · Dlink

CVE-2026-4196

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 has been found 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. This impacts the function cgi_recovery/cgi_backup_now/cgi_set_schedule/cgi_set_rsync_server of the file /cgi-bin/remote_backup.cgi. The manipulation leads to command injection. The attack is possible to be carried out remotely. The exploit has been disclosed to the 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 · high confidence

Critical command injection vulnerability in D-Link network storage devices (multiple models DNS/DNR series). The remote_backup.cgi script contains vulnerable functions (cgi_recovery, cgi_backup_now, cgi_set_schedule, cgi_set_rsync_server) that fail to sanitize user input, allowing arbitrary OS command execution with root privileges. Public exploit availability and CVSS 9.8 indicate active exploitation is likely.

MitigationContact D-Link for available firmware updates; if none exist, immediately network-isolate affected devices behind firewalls and disable remote management access to mitigate exploitation until device replacement.

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
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
Dns 320l FirmwareOperating system
Affected:<= 2026-02-05
Dns 320lw FirmwareOperating system
Affected:<= 2026-02-05
Dns 321 FirmwareOperating system
Affected:<= 2026-02-05
Dns 322l FirmwareOperating system
Affected:<= 2026-02-05
Dns 323 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 D-Link NAS model
    Access the device web interface or check the device label to confirm the exact model (e.g., DNS-320, DNS-320L, DNS-323, etc.). Match against the list of affected models.
    Affected if The model is one of: DNS-1550-04, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNS-322L, or DNS-323.
  2. Check the installed firmware version
    Log into the device web interface and navigate to the System or Status section to view the firmware version. Alternatively, check the firmware file name if you have physical access or SSH access to the device.
    Affected if The firmware version date is 2026-02-05 or earlier.
  3. Verify if the remote_backup.cgi script is present and accessible
    Attempt to access the CGI script via HTTP/HTTPS: http://[device-ip]/cgi-bin/remote_backup.cgi. Check if the script responds or returns any output.
    Affected if The script is present and returns a response, indicating the backup feature is available on the device.
  4. Check if remote management or cloud features are enabled
    In the device web interface, look for settings under Backup, Remote Access, or Cloud features. Check if remote backup functionality is configured or enabled.
    Affected if Remote backup features are enabled or configured, making the vulnerable functions accessible.
  5. Determine network exposure of the management interface
    Check if the device web interface (port 80/443) is accessible from the internet or untrusted networks. Review firewall rules and port forwarding configurations.
    Affected if The device management interface is exposed to the internet or untrusted networks, allowing unauthenticated attackers to reach the vulnerable CGI script.

The environment is affected if you have a D-Link NAS model from the list with firmware dated 2026-02-05 or earlier, and the remote_backup.cgi script is accessible either locally or remotely, especially if the management interface is internet-facing.

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

Contact D-Link for available firmware updates; if none exist, immediately network-isolate affected devices behind firewalls and disable remote management access to mitigate exploitation until device replacement.

Fix this in Dns 1550 04 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2026-4196 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