Dir 823g FirmwareOperating system · Dlink

CVE-2020-25366

CRITICAL · 9.1 CVSS v3.1 Published 2021-11-04
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
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
An issue in the component /cgi-bin/upload_firmware.cgi of D-Link DIR-823G REVA1 1.02B05 allows attackers to cause a denial of service (DoS) via unspecified vectors.

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

A denial of service vulnerability exists in the firmware upload CGI component (/cgi-bin/upload_firmware.cgi) of D-Link DIR-823G REVA1 routers running firmware version 1.02B05. The vulnerability allows remote attackers to crash or disable the device via the unspecified firmware upload functionality.

MitigationRestrict network access to the router's management interface using firewall rules or by disabling remote administration. If possible, limit access to trusted IP addresses only. Monitor for unauthorized firmware upload attempts.

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 823g FirmwareOperating system
Affected:= 1.02b05

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
None
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 device model
    Access the router's web administration interface or check the device label to confirm the exact model number is DIR-823G REVA1
    Affected if The device is not a D-Link DIR-823G REVA1 model
  2. Check the installed firmware version
    Log into the router's web interface and navigate to the Status or System section to view the firmware version, or check via CLI if available
    Affected if The firmware version is exactly 1.02B05
  3. Verify the CGI firmware upload component exists
    Attempt to access http://[router-ip]/cgi-bin/upload_firmware.cgi or check the firmware image for this CGI file
    Affected if The upload_firmware.cgi script is present on the device
  4. Confirm web-based management is accessible
    Check if the router's HTTP/HTTPS management interface is reachable from the network, either locally or remotely
    Affected if The web interface is exposed to untrusted networks (remote management enabled)

A user is affected if they have a D-Link DIR-823G REVA1 router running firmware version 1.02B05 with the web management interface accessible to the 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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Restrict network access to the router's management interface using firewall rules or by disabling remote administration. If possible, limit access to trusted IP addresses only. Monitor for unauthorized firmware upload attempts.

Fix this in Dir 823g Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-25366 — 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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-25366 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
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