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Dnr 202l FirmwareOperating system · Dlink

CVE-2026-4206

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 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 affects the function FMT_rebuild_diskmgr/FMT_create_diskmgr/ScanDisk_run_e2fsck of the file /cgi-bin/dsk_mgr.cgi. Performing a manipulation results in command injection. The attack is possible to be carried out remotely. The exploit has been made public and could 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

Multiple D-Link NAS devices contain a command injection vulnerability in /cgi-bin/dsk_mgr.cgi via the FMT_rebuild_diskmgr, FMT_create_diskmgr, and ScanDisk_run_e2fsck functions. Attackers can inject arbitrary OS commands through manipulation of these disk management functions.

MitigationRestrict network access to affected devices, disable remote CGI access if possible, apply available firmware updates, and consider replacing end-of-life devices.

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 D-Link NAS device model
    Access the device web interface or check the device label to confirm the exact model number. Affected models are: DNR-202L, DNR-326, DNS-1100-4, DNS-120, DNS-1200-05, DNS-1550-04, DNS-315L, DNS-320
    Affected if The device model matches one of the listed affected models
  2. Check the installed firmware version
    Log into the device web interface and navigate to System > Firmware Upgrade or System Information page. Compare the firmware build date against 2026-02-05. Alternatively, check via CLI if SSH/telnet is enabled using 'cat /etc/version' or similar command that displays firmware info
    Affected if The firmware build date is on or before 2026-02-05
  3. Verify the vulnerable CGI endpoint is reachable
    Attempt to access https://[device-ip]/cgi-bin/dsk_mgr.cgi from within the local network. A successful HTTP 200 response indicates the endpoint exists and is accessible
    Affected if The /cgi-bin/dsk_mgr.cgi endpoint responds to requests (indicating CGI is enabled)
  4. Confirm disk management interface is accessible
    Log into the device as an administrator and navigate to Storage > Disk Management or similar disk configuration section. Check if the functions FMT_rebuild_diskmgr, FMT_create_diskmgr, or ScanDisk_run_e2fsck can be accessed or triggered
    Affected if Disk management features are enabled and accessible to authenticated users or via the CGI interface
  5. Review access logs for suspicious disk management requests
    Check device logs (typically found in System > Logs or /var/log) for any unusual POST requests to /cgi-bin/dsk_mgr.cgi with unexpected parameters, especially those containing shell metacharacters like ; | & $ or backticks
    Affected if Logs show disk management CGI requests with potential command injection patterns

You are affected if your D-Link NAS model matches one of the eight listed models AND your firmware build date is on or before 2026-02-05, and the disk management CGI endpoint is accessible on your network.

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

Restrict network access to affected devices, disable remote CGI access if possible, apply available firmware updates, and consider replacing end-of-life devices.

Fix this in Dnr 202l Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2026-4206 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