Package Instance

Improper Input Validation
If an application passes unvalidated user input as the file for which MIME type validation should occur, then arbitrary arguments are passed to the underlying file command.

Cross-site Scripting
The debug handler in Symfony has an XSS via an array key during exception pretty printing in `ExceptionHandler.php`, as demonstrated by a `/_debugbar/open?op`=get` URI.

Cross-Site Request Forgery (CSRF)
By default, a user's session is invalidated when the user is logged out. This behavior can be disabled through the `invalidate_session` option. In this case, CSRF tokens were not erased during logout which allowed for CSRF token fixation.

Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition)
The UriSigner was subjectto timing attacks.

Insufficient Session Expiration
The `PDOSessionHandler` class allows storing sessions on a PDO connection. Under some configurations and with a well-crafted payload, it was possible to do a denial of service on a Symfony application without too much resources.

URL Rewrite vulnerability
An issue in Symfony arises from support for a (legacy) IIS header that lets users override the path in the request URL via the `X-Original-URL` or `X-Rewrite-URL` HTTP request header. These headers are designed for IIS support, but it's not verified that the server is in fact running IIS, which means anybody who can send these requests to an application can trigger this. This affects `\Symfony\Component\HttpFoundation\Request::prepareRequestUri()` where `X-Original-URL` and `X_REWRITE_URL` are both used. The fix drops support for these methods so that they cannot be used as attack vectors such as web cache poisoning.

Session Fixation
A session fixation vulnerability within the `Guard` login feature may allow an attacker to impersonate a victim towards the web application if the session id value was previously known to the attacker.