CVE-2020-12255
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 · uneditedrConfig 3.9.4 is vulnerable to remote code execution due to improper validation in the file upload functionality. vendor.crud.php accepts a file upload by checking content-type without considering the file extension and header. Thus, an attacker can exploit this by uploading a .php file to vendor.php that contains arbitrary PHP code and changing the content-type to image/gif.
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 confidencerConfig 3.9.4 contains a file upload vulnerability in vendor.crud.php where the application only validates the Content-Type header sent by the client, allowing attackers to bypass this check by uploading PHP files containing malicious code while spoofing the Content-Type as image/gif, leading to remote code execution.
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= 3.9.4CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Confirm rConfig installation and versionIdentify the installed rConfig version by accessing the admin interface or checking version files in the web root. Compare the version number against 3.9.4.Affected if The installed version is exactly 3.9.4.
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Locate vendor.crud.phpSearch the web directory for the file vendor.crud.php, which handles file uploads in the application.Affected if The file vendor.crud.php exists in the application web root.
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Verify upload functionality is accessibleDetermine if the file upload endpoint handled by vendor.crud.php is reachable via HTTP POST requests without authentication restrictions.Affected if The upload functionality in vendor.crud.php is exposed and accessible to unauthenticated or low-privilege users.
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Check upload directory PHP execution permissionsIdentify the upload directory used by rConfig and verify if the web server configuration allows PHP files in that directory to be executed.Affected if The upload directory permits execution of uploaded PHP files (no execution restrictions configured).
A user is affected if they are running rConfig version 3.9.4 with the vendor.crud.php upload functionality accessible and the upload directory allowing PHP execution.
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 dataImplement proper file validation by checking both the file extension against an allowed whitelist and verifying the actual file content/magic bytes, while ensuring the upload directory has no PHP execution permissions.
- Consultation2.0 h
- Implementation4.0 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 $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-12255 — 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-2020-12255 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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- 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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