CVE-2026-4214
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 · uneditedA flaw 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 issue affects the function UPnP_AV_Server_Path_Setting of the file /cgi-bin/app_mgr.cgi. Executing a manipulation can lead to stack-based buffer overflow. The attack may be launched remotely. The exploit has been published 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 confidenceA stack-based buffer overflow vulnerability exists in the UPnP_AV_Server_Path_Setting function of /cgi-bin/app_mgr.cgi on multiple D-Link DNS and DNR series NAS devices. The vulnerability allows remote attackers to execute arbitrary code via crafted HTTP requests due to insufficient bounds checking when handling path parameters.
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<= 2026-02-05<= 2026-02-05<= 2026-02-05<= 2026-02-05<= 2026-02-05<= 2026-02-05<= 2026-02-05<= 2026-02-05CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify device modelCheck the device label or web interface for the exact model number (Dnr 202l, Dnr 326, Dns 1100 4, Dns 120, Dns 1200 05, Dns 1550 04, Dns 315l, or Dns 320)Affected if The device is one of these D-Link models: DNR 202l, DNR 326, DNS 1100 4, DNS 120, DNS 1200 05, DNS 1550 04, DNS 315l, or DNS 320
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Check firmware versionAccess the device web interface (typically at http://<device_ip>) and navigate to the firmware or system information page, or use the device's firmware upgrade utility to view the current versionAffected if The firmware version date is on or before 2026-02-05 (or the version string indicates a date prior to that)
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Verify vulnerable CGI endpoint existsAttempt to access http://<device_ip>/cgi-bin/app_mgr.cgi via HTTP request and observe the responseAffected if The endpoint responds (indicating the CGI script is present and accessible)
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Confirm UPnP is enabledCheck the device settings page for UPnP (Universal Plug and Play) or UPnP AV server configuration; the vulnerable function is UPnP_AV_Server_Path_SettingAffected if UPnP or UPnP AV server functionality is enabled on the device
A user is affected if they own one of the listed D-Link devices (DNR or DNS series) running firmware dated 2026-02-05 or earlier, where the app_mgr.cgi endpoint is accessible and UPnP functionality is enabled.
Generated from the published advisory. Verify against your own configuration.
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 dataApply vendor firmware updates if available; otherwise disable the UPnP AV server service or isolate affected devices from untrusted networks. Given these are legacy devices, consider replacement if patches are unavailable.
- Consultation4.0 h
- Implementation8.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4214 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-4214 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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