CVE-2021-20104
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 · uneditedMachform prior to version 16 is vulnerable to unauthenticated remote code execution due to insufficient sanitization of file attachments uploaded with forms through upload.php.
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 confidenceMachform versions prior to 16 contain an unauthenticated remote code execution vulnerability in upload.php. Attackers can exploit insufficient sanitization of file attachments uploaded through forms to upload and execute malicious files.
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< 16CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Locate Machform installation and upload.phpSearch the web server for the Machform directory, typically under the web root. Verify the presence of upload.php within the machform directory structure.Affected if The upload.php file exists in the Machform installation directory
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Identify the Machform versionCheck the version file (usually version.php in the includes folder) or log into the Machform admin panel to view the version number displayed in the footer or about section.Affected if The installed version is less than 16 (e.g., 15.x, 14.x, etc.)
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Confirm file upload is enabled on any formsAccess the Machform admin panel and review the form editor for any form fields. Check if the file upload field type has been added and enabled on any published form.Affected if At least one form has a file upload field enabled and is in use
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Verify upload.php is externally accessibleAttempt to access the upload.php endpoint directly via HTTP/HTTPS (e.g., https://yourdomain.com/machform/upload.php) without authentication. A successful connection without being redirected to a login page indicates the endpoint is exposed.Affected if The upload.php endpoint responds without requiring authentication
All four conditions must be true for the environment to be affected: Machform version below 16 is installed, upload.php exists, file upload fields are enabled on at least one form, and the upload endpoint is externally accessible without authentication.
Generated from the published advisory. Verify against your own configuration.
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 data16
Upgrade to Machform version 16 or later which includes proper file sanitization for form attachments.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20104 — 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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20104 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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