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Dir 878 FirmwareOperating system · Dlink

CVE-2021-30072

CRITICAL · 9.8 CVSS v3.1 Published 2021-04-02
Fix available
A fix is available. Upgrade to after 1.30b08 or later.
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
An issue was discovered in prog.cgi on D-Link DIR-878 1.30B08 devices. Because strcat is misused, there is a stack-based buffer overflow that does not require authentication.

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

A stack-based buffer overflow exists in prog.cgi on D-Link DIR-878 routers (firmware 1.30B08) due to improper use of the unsafe strcat function for string concatenation. This allows remote attackers to execute arbitrary code without authentication.

MitigationReplace the end-of-life D-Link DIR-878 router with a supported device; if immediate replacement is not possible, block external access to the device's web interface.

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 878 FirmwareOperating system
Affected:<= 1.30b08

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 device model
    Access the router's web interface or check the device label/menu to confirm the model is D-Link DIR-878
    Affected if The device is not a D-Link DIR-878 router, then it is not affected by this specific CVE
  2. Check the firmware version
    Log into the router web interface and navigate to the Status or Firmware Upgrade page to view the current firmware version. Compare against the affected version 1.30B08 or earlier.
    Affected if The installed firmware version is 1.30B08 or any version lower than 1.30B08
  3. Verify the web interface is accessible
    Attempt to access the router's web interface from the network where the router is deployed. Confirm http/https ports (typically 80/443) are listening on the device.
    Affected if The router's web interface is accessible to network attackers (internal or external), making exploitation possible
  4. Confirm prog.cgi is present
    Attempt to access the CGI endpoint directly by navigating to http://<router-ip>/prog.cgi or similar path. The vulnerability exists in this binary.
    Affected if The prog.cgi endpoint responds to requests, indicating the vulnerable component is present and exposed

The environment is affected if the device is a D-Link DIR-878 running firmware version 1.30B08 or earlier, and the web interface (including prog.cgi) is accessible to potential attackers.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 1.30b08
Interim mitigation

Replace the end-of-life D-Link DIR-878 router with a supported device; if immediate replacement is not possible, block external access to the device's web interface.

Recommended fix Moderate confidence

Firmware version newer than 1.30b08 (check D-Link support for exact patched release)

  1. Check D-Link supportannouncement.us.dlink.com and www.dlink.com for the latest DIR-878 firmware version
  2. Identify the firmware version that addresses CVE-2021-30072 (should be newer than 1.30b08)
  3. Download the firmware update from the official D-Link support website only
  4. Access the D-Link DIR-878 web management interface
  5. Navigate to the Administration or System settings section
  6. Locate the Firmware Upgrade or Update option
  7. Upload the downloaded firmware file
  8. Wait for the upgrade process to complete - do not power off the device
Caveat Review D-Link release notes for any configuration or feature changes between versions

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

Fix this in Dir 878 Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
17.0 hours of engineering $3,000
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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-2021-30072 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