CVE-2021-47936
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 · uneditedOpenCATS 0.9.4 contains a remote code execution vulnerability that allows unauthenticated attackers to execute arbitrary commands by uploading malicious PHP files disguised as resume attachments. Attackers can upload PHP payloads through the careers job application endpoint and execute system commands via POST requests to the uploaded file in the upload directory.
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 confidenceOpenCATS 0.9.4 has an unauthenticated remote code execution vulnerability in its careers job application module. The system accepts file uploads for resume attachments without proper validation, allowing attackers to upload malicious PHP files. These PHP payloads can then be executed via HTTP POST requests to the upload directory, granting arbitrary command execution on the server.
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 checksWork through these to decide whether this CVE applies to you.
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Identify OpenCATS installation and versionLocate the OpenCATS installation directory and check the version file (typically version.php or similar) or check the web interface version displayAffected if The installed version is 0.9.4 or falls within the affected range around 0.9.4
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Verify the careers/job application feature is enabledCheck if the careers module or job application functionality is accessible on the OpenCATS web interface (typically at /careers or /index.php?m=careers)Affected if The careers application feature is active and publicly accessible without authentication
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Confirm the upload directory is web-accessibleIdentify the upload directory path from the application configuration and verify it is reachable via HTTP/HTTPS from the web server document rootAffected if The upload directory is located within the web-accessible path and can be accessed via URL
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Check if PHP execution is permitted in the upload directoryInspect the web server configuration (Apache .htaccess or nginx config) or the upload directory for rules that allow or deny PHP executionAffected if PHP execution is allowed in the upload directory (no Deny/Disable directives for .php files)
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Look for suspicious PHP files in the upload directoryList all files in the upload directory and identify any with .php extensions that were not explicitly uploaded by administratorsAffected if Any unexpected PHP files exist in the upload directory that could indicate exploitation
A user is affected if OpenCATS version 0.9.4 (or similar) is running with the careers application feature enabled, the upload directory is web-accessible, and PHP execution is allowed in that directory.
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 dataDisable PHP execution in upload directories via web server configuration (e.g., .htaccess or nginx config), implement strict file type validation with magic byte checking, and restrict uploaded files to safe formats like PDF/DOCX. If a patched version exists, upgrade immediately.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
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Free · runs locallyCheck whether your project pulls in CVE-2021-47936 — 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-2021-47936 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