CVE-2009-4412
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 · uneditedUnrestricted file upload vulnerability in Serendipity before 1.5 allows remote authenticated users to execute arbitrary code by uploading a file with an executable extension followed by a safe extension, then accessing it via a direct request to the file in an unspecified directory. NOTE: some of these details are obtained from third party information.
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 confidenceSerendipity before version 1.5 contains an unrestricted file upload vulnerability where authenticated users can bypass security controls by uploading files with double extensions (e.g., 'shell.php.jpg'). The application only validates the final safe extension (.jpg) while the file is stored with the executable extension (.php) accessible via direct HTTP request, allowing arbitrary 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<= 1.5= 0.3= 0.4= 0.5= 0.6= 0.7= 0.7.1= 0.8= 0.8.1= 0.8.2= 0.8.3= 0.8.4CVSS 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
- M
- Authentication
- Single
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/Au:S/C:P/I:P/A:P
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 installed Serendipity versionLocate the serendipity version file (typically in include/db.inc.php or a VERSION file in the Serendipity root directory) and read the version numberAffected if The installed version is 1.5 or lower, or matches any of these exact versions: 0.3, 0.4, 0.5, 0.6, 0.7, 0.7.1, 0.8, 0.8.1, 0.8.2, 0.8.3, 0.8.4
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Verify if file upload is enabled for non-admin usersAccess the Serendipity administration panel, navigate to Configuration -> Uploads, or inspect the serendipity_config table in the database for upload-related settings (such as 'allowNonAdminUpload' or similar upload permissions)Affected if Non-admin users have the ability to upload files to the system
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Locate the uploads directory and check file permissionsFind the uploads directory (typically /uploads or /files under the Serendipity web root). List files with double extensions (e.g., *.php.*, *.php.jpg) using a command like 'find . -name "*.php.*"' or manually inspect directory contentsAffected if The uploads directory exists and contains files with double extensions where a script extension precedes a safe extension (e.g., shell.php.jpg)
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Verify web server configuration for uploaded filesCheck the web server (Apache/nginx) configuration to determine if uploaded files are served from a directory that allows script execution (e.g., uploads folder has AllowOverride All or lacks AddType restrictions for PHP)Affected if Uploaded files are stored in a web-accessible directory where the web server will execute .php files without restriction
You are affected if your Serendipity installation is version 1.5 or lower, non-admin users can upload files, and the web server is configured to execute PHP files in the uploads 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 dataUpgrade to Serendipity 1.5 or later. As an interim measure, disable file upload functionality for non-admin users, configure the web server to prevent execution of uploaded files, and implement strict server-side validation that checks actual file content/MIME type rather than relying on file extensions.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2009-4412 — 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-2009-4412 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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- Version or environment caveats, and links to real fixes
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