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Security Advisory – Symfony2 Local File Disclosure Vulnerability


Sense of Security – Security Advisory – SOS-12-002

Release Date. 05-Mar-2012
Last Update.
Vendor Notification Date. 24-Feb-2012
Product. Symfony2
Platform. PHP
Affected versions. 2.0.x – 2.0.10
Severity Rating. Medium
Impact. Exposure of sensitive information
Attack Vector. Remote without authentication
Solution Status. Vendor patch / Upgrade to 2.0.11
CVE reference. CVE- Not yet assigned



The XMLEncoder component of Symfony 2.0.x fails to disable external  entities when parsing XML. In the Symfony2 framework the XML class may be used to deserialize objects or as part of a client/server API. By using  external entities it is possible to include arbitrary files from the file system. Any application written in Symfony2 that parses user supplied XML is affected.


Proof of Concept.
$serializer = new Serializer(array(), array(
‘xml’ => new \Symfony\Component\Serializer\Encoder\XmlEncoder()

$x = $serializer->decode(‘<!DOCTYPE scan



// $x will now contain a copy of /etc/passwd base64 encoded.



Upgrade to Symfony 2.0.11 or apply the vendor provided patch.


Discovered by.

Phil Taylor from Sense of Security Labs.