dbcve.org
Dap 1880ac FirmwareOperating system · Dlink

CVE-2021-20695

HIGH · 8.8 CVSS v3.1 Published 2021-04-26
Fix available
A fix is available. Upgrade to after 1.21 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
Improper following of a certificate's chain of trust vulnerability in DAP-1880AC firmware version 1.21 and earlier allows a remote authenticated attacker to gain root privileges 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 · high confidence

This vulnerability in DAP-1880AC firmware versions 1.21 and earlier involves improper certificate chain of trust validation. A remote authenticated attacker can exploit this weakness to gain root privileges, likely by presenting a malicious certificate that the device incorrectly trusts due to incomplete or missing validation of the certificate chain.

MitigationUpdate to the latest firmware version once available. In the interim, restrict network access to the device and avoid untrusted networks to reduce exposure to man-in-the-middle attacks exploiting this certificate validation flaw.

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
Dap 1880ac FirmwareOperating system
Affected:<= 1.21

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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. Verify device model is D-Link DAP-1880AC
    Log into the device web management interface or check the physical device label to confirm the exact model number.
    Affected if Device model is DAP-1880AC
  2. Check installed firmware version
    Access the router web interface (typically 192.168.0.1), navigate to Status or System Info page, and record the firmware version displayed.
    Affected if Firmware version is 1.21 or any version lower (e.g., 1.20, 1.10, etc.)
  3. Confirm remote management access is enabled
    In the web interface, go to System or Management settings and check if Remote Management, HTTPS Management, or SSL Admin access is enabled and configure which IP addresses can access it.
    Affected if Remote HTTPS/SSL management is enabled and accessible to network attackers
  4. Check device network exposure
    Determine if the device management interface is reachable from untrusted networks (WAN/Internet) by testing connectivity to the device's public IP on ports 443 or 4433, or by reviewing port forwarding/firewall rules.
    Affected if Device management interface is exposed directly to the Internet or untrusted networks
  5. Review SSL certificate configuration
    Access the device SSL/TLS certificate settings in the management interface and verify whether custom certificates are configured or if the device uses its default self-signed certificate.
    Affected if Device uses default certificates or has no custom certificate chain configured

You are affected if you have a DAP-1880AC device running firmware version 1.21 or earlier with remote management or SSL administration features enabled and accessible to network 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 1.21
Interim mitigation

Update to the latest firmware version once available. In the interim, restrict network access to the device and avoid untrusted networks to reduce exposure to man-in-the-middle attacks exploiting this certificate validation flaw.

Recommended fix Moderate confidence

Latest available DAP-1880AC firmware version from D-Link (version > 1.21)

  1. 1. Visit the D-Link support website (dlink-jp.com or dlink.com) and navigate to the product support section for DAP-1880AC
  2. 2. Locate and download the latest available firmware version for DAP-1880AC (ensure the version is newer than 1.21)
  3. 3. Access the DAP-1880AC web management interface using an administrator account
  4. 4. Navigate to the firmware upgrade or system settings section of the web interface
  5. 5. Upload the downloaded firmware file and initiate the upgrade process
  6. 6. Wait for the device to complete the firmware update and reboot automatically
  7. 7. After reboot, verify the firmware version has been updated successfully and confirm normal device operation
Caveat Firmware updates may temporarily disrupt wireless connectivity; ensure stable power during the upgrade process

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

Fix this in Dap 1880ac Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,920
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,072.

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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-2021-20695 in production — separate from our analysis above.

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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