dbcve.org
Missing AuthenticationWeakness · CWE-306

CVE-2021-47940

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-10
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
WordPress Plugin Download From Files version 1.48 and earlier contains an arbitrary file upload vulnerability that allows unauthenticated attackers to upload malicious files by exploiting the AJAX fileupload action. Attackers can send POST requests to the admin-ajax.php endpoint with the download_from_files_617_fileupload action, manipulating the allowExt parameter to bypass file type restrictions and upload executable files like PHP shells to the web root.

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

The WordPress 'Download From Files' plugin versions 1.48 and earlier contains an unauthenticated arbitrary file upload vulnerability in the AJAX fileupload action (download_from_files_617_fileupload). Attackers can bypass file type restrictions by manipulating the allowExt parameter when sending POST requests to admin-ajax.php, allowing execution of malicious PHP files in the web root.

MitigationUpgrade the 'Download From Files' plugin to version 1.49 or later, or remove the plugin if not needed. If exploitation is suspected, conduct a full compromise assessment to identify and remove any malicious files already uploaded.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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. Verify plugin version
    Navigate to WordPress admin > Plugins > Installed Plugins > Download From Files and check the Version field, or inspect the plugin header in wp-content/plugins/download-from-files/download-from-files.php
    Affected if The installed version is 1.48 or earlier
  2. Confirm the vulnerable AJAX action exists
    Inspect the plugin source file for the function handling 'download_from_files_617_fileupload' AJAX action, typically in the main plugin PHP file, and verify it accepts the allowExt parameter without proper validation
    Affected if The AJAX action 'download_from_files_617_fileupload' is present and the allowExt parameter can be manipulated
  3. Test unauthenticated access to admin-ajax.php
    Send a GET or POST request to /wp-admin/admin-ajax.php?action=download_from_files_617_fileupload without authenticating (no valid WordPress nonce or session)
    Affected if The server responds to the request (returns any HTTP response other than 401/403) indicating the endpoint is accessible to unauthenticated users
  4. Inspect web root for suspicious PHP files
    List all PHP files in the WordPress web root directory (typically the folder containing wp-config.php) and review any files with names that appear random, encoded, or match common webshell patterns
    Affected if Unexpected or unknown PHP files exist in the web root that were not intentionally uploaded by administrators

A user is affected if the Download From Files plugin version is 1.48 or earlier and the admin-ajax.php endpoint is accessible to unauthenticated users, or if unexpected PHP files exist in the web root.

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

Upgrade the 'Download From Files' plugin to version 1.49 or later, or remove the plugin if not needed. If exploitation is suspected, conduct a full compromise assessment to identify and remove any malicious files already uploaded.

Recommended fix Moderate confidence

Download From Files version 1.49 or later

  1. Check the current version of the Download From Files plugin in WordPress admin under Plugins > Installed Plugins
  2. Navigate to the WordPress Plugin Repository at wordpress.org to find the latest fixed version
  3. Update the plugin through WordPress admin: Plugins > Add New > Upload or update directly from the Plugins page
  4. After updating, verify the new version number reflects the patched release
  5. Confirm the vulnerability is patched by ensuring the admin-ajax.php?action=download_from_files_617_fileupload endpoint no longer accepts unauthenticated file uploads

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $910
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Scan for this in your stack

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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-2021-47940 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