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Dir 842 FirmwareOperating system · Dlink

CVE-2023-39666

CRITICAL · 9.8 CVSS v3.1 Published 2023-08-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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
D-Link DIR-842 fw_revA_1-02_eu_multi_20151008 was discovered to contain multiple buffer overflows in the fgets function via the acStack_120 and acStack_220 parameters.

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

The D-Link DIR-842 router firmware contains buffer overflow vulnerabilities in the fgets function, triggered via the acStack_120 and acStack_220 HTTP parameters. With a CVSS score of 9.8, this critical vulnerability likely allows remote attackers to execute arbitrary code by sending specially crafted oversized input to these parameters.

MitigationApply available firmware patches from D-Link; if no patch exists, restrict administrative interface access to trusted networks only via firewall rules.

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
Dir 842 FirmwareOperating system
Affected:= 1.05b02

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. Confirm D-Link DIR-842 model
    Access router web interface or check physical device label for model number DIR-842
    Affected if Model is not D-Link DIR-842
  2. Check firmware version
    Navigate to router web interface Status or Administration page to view firmware version, or check via CLI if accessible
    Affected if Firmware version equals 1.05b02
  3. Verify HTTP management interface is accessible
    Attempt to access router web interface on ports 80 or 443 from network perspective
    Affected if HTTP/HTTPS management interface is exposed and reachable
  4. Check remote admin access configuration
    In router web interface, look for Remote Management or Access Control settings; determine if admin interface is accessible from WAN/Internet
    Affected if Remote management is enabled and accessible from untrusted networks

User is affected if they run D-Link DIR-842 firmware version 1.05b02 and have the HTTP management interface accessible, particularly from untrusted networks.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply available firmware patches from D-Link; if no patch exists, restrict administrative interface access to trusted networks only via firewall rules.

Fix this in Dir 842 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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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-2023-39666 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
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