Dir 806 FirmwareOperating system · Dlink

CVE-2025-4340

CRITICAL · 9.8 CVSS v3.1 Published 2025-05-06
Fix available
A fix is available. Upgrade to after 100cnb11 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 classified as critical has been found in D-Link DIR-890L and DIR-806A1 up to 100CNb11/108B03. Affected is the function sub_175C8 of the file /htdocs/soap.cgi. The manipulation leads to command injection. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. 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
How this class of weakness works · CWE-74

Untrusted input crosses into a downstream interpreter — SQL, a shell, an HTML page, an LDAP query — without being kept separate from the commands around it, so the attacker's data is read as instructions. This is the parent class behind SQL injection, cross-site scripting, and command injection alike. The durable fix is the same everywhere: keep data and code apart at every boundary, using parameterisation or context-aware encoding rather than building interpreted strings by concatenation.

General guidance for the injection class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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 806 FirmwareOperating system
Affected:<= 100cnb11
Dir 890l FirmwareOperating system
Affected:<= 1.08b03

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

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
Upgrade available Upgrade to a release after 100cnb11
Recommended fix High confidence
  1. 1. Discontinue use of affected D-Link DIR-806 and DIR-890L devices as they have reached end-of-support and no official firmware patches are available for CVE-2025-4340.
  2. 2. Replace affected devices with currently supported router models from D-Link or other vendors that receive active security updates.
  3. 3. If continued use is absolutely necessary, isolate the device on a restricted network segment with firewall rules blocking all external access to the device's management interface.
  4. 4. Disable any remote management features (WAN access, cloud services) on the affected device.
  5. 5. Monitor for any future firmware releases from D-Link, though the official description indicates these products are no longer supported.
Caveat Both DIR-806 (≤100CNb11) and DIR-890L (≤108B03) are end-of-life products with no official security patches available - replacement with a supported device is the only remediation path

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

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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-2025-4340 in production — separate from our analysis above.

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