Symfony1 is a community fork of symfony 1.4 with DIC, form enhancements, latest Swiftmailer, better performance, composer compatible and PHP 8 support. Symfony 1 has a gadget chain due to vulnerable Swift Mailer dependency that would enable an attacker to get remote code execution if a developer unserialize user input in his project. This vulnerability present no direct threat but is a vector that will enable remote code execution if a developper deserialize user untrusted data. Symfony 1 depends on Swift Mailer which is bundled by default in vendor directory in the default installation since 1.3.0. Swift Mailer classes implement some __destruct() methods. These methods are called when php destroys the object in memory. However, it is possible to include any object type in $this->_keys to make PHP access to another array/object properties than intended by the developer. In particular, it is possible to abuse the array access which is triggered on foreach($this->_keys …) for any class implementing ArrayAccess interface. This may allow an attacker to execute any PHP command which leads to remote code execution. This issue has been addressed in version 1.5.18. Users are advised to upgrade. There are no known workarounds for this vulnerability.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.