CVE-2009-4137
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 · uneditedThe loadContentFromCookie function in core/Cookie.php in Piwik before 0.5 does not validate strings obtained from cookies before calling the unserialize function, which allows remote attackers to execute arbitrary code or upload arbitrary files via vectors related to the __destruct function in the Piwik_Config class; php://filter URIs; the __destruct functions in Zend Framework, as demonstrated by the Zend_Log destructor; the shutdown functions in Zend Framework, as demonstrated by the Zend_Log_Writer_Mail class; the render function in the Piwik_View class; Smarty templates; and the _eval function in Smarty.
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 confidencePiwik versions before 0.5 contain an insecure deserialization vulnerability in the loadContentFromCookie function of core/Cookie.php. The function passes unvalidated cookie data directly to PHP's unserialize() function, allowing attackers to inject malicious serialized objects that trigger PHP magic methods (__destruct, shutdown handlers) in Piwik_Config, Zend Framework, and Smarty template classes to achieve 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= 0.2.25= 0.2.26= 0.2.27= 0.2.28= 0.2.29= 0.2.30= 0.2.31= 0.2.32CVSS 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
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/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 Piwik/Matomo versionCheck the version file in your installation. Common locations: /path/to/piwik/core/Version.php or /path/to/matomo/core/Version.php. Look for a variable containing the version number (e.g., const VERSION = 'x.x.x';).Affected if The version is 0.2.25, 0.2.26, 0.2.27, 0.2.28, 0.2.29, 0.2.30, 0.2.31, or 0.2.32 (any version before 0.5 in the 0.2.x line).
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Locate the vulnerable Cookie.php fileFind core/Cookie.php in your Piwik/Matomo installation directory. Open the file and search for the function named 'loadContentFromCookie'.Affected if The function loadContentFromCookie exists and contains a call to unserialize() without prior validation of the input parameter.
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Verify cookie handling is enabledCheck if cookie-based session handling or tracking is active. Look for cookie-related configuration in config/config.ini.php or check if the Piwik tracking cookie (typically named 'piwik_ignore' or similar session cookies) is being set in your browser when visiting the site.Affected if Cookie-based session handling or cookie-based features are enabled in the Piwik/Matomo configuration.
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Confirm unserialize is called on cookie dataIn core/Cookie.php, examine the loadContentFromCookie function. Trace whether cookie values (from $_COOKIE) are passed directly to unserialize() without any validation or sanitization.Affected if The function retrieves cookie data and passes it directly to unserialize() without validation steps between retrieval and deserialization.
Your environment is affected if you are running Piwik versions 0.2.25 through 0.2.32 (or any pre-0.5 version) and the loadContentFromCookie function in core/Cookie.php uses unserialize() on unvalidated cookie data with cookie handling enabled.
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 Piwik 0.5 or later which implements proper validation of cookie data before unserialization. If immediate upgrade is not feasible, implement input validation on all cookie values and consider temporarily disabling cookie-based session handling as a defensive measure.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-4137 — 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-2009-4137 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
- No spam, self-promotion, credentials, or personal data