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Dap 2020 FirmwareOperating system · Dlink

CVE-2021-27249

HIGH · 8.8 CVSS v3.1 Published 2021-04-14
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
93/100
Remediation priority · Urgent
No privileges Zero-click Patch available

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
This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DAP-2020 v1.01rc001 Wi-Fi access points. Authentication is not required to exploit this vulnerability. The specific flaw exists within the processing of CGI scripts. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-11369.

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-78

User input reaches a shell or system command without being fully separated from the command itself, so an attacker can append their own instructions. Because these run with the application's privileges, it often means full control of the host. The lasting fix is to avoid the shell entirely — call APIs directly and pass arguments as data, never as concatenated strings.

General guidance for the os command 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
Dap 2020 FirmwareOperating system
Affected:= 1.01

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/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
Patch available Apply the vendor patch
Vendor patch supportannouncement.us.dlink.com →
Recommended fix Moderate confidence

Check vendor announcement for fixed firmware version (vendor patch available at SAP10201)

  1. 1. Visit the D-Link vendor announcement page at https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10201 to obtain the patched firmware version for DAP-2020.
  2. 2. Download the patched firmware version from the official D-Link support site.
  3. 3. Access the D-Link DAP-2020 web management interface.
  4. 4. Navigate to the firmware upgrade or system settings section.
  5. 5. Upload and apply the patched firmware version.
  6. 6. After reboot, verify the device is functioning correctly with the new firmware.
Caveat Firmware upgrades may temporarily disrupt connectivity; backup configuration before upgrading if possible

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-2021-27249 in production — separate from our analysis above.

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What this is

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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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