Package Instance

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.

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.

Improper Authentication
In Symfony, a vulnerability would allow an attacker to authenticate as a privileged user on sites with user registration and remember me login functionality enabled.

Improper Authentication
An issue was discovered in the Ldap component in Symfony. It allows remote attackers to bypass authentication by logging in with a `null` password and valid username, which triggers an unauthenticated bind.

Prevent user enumeration using Guard or the new Authenticator-based Security
Description
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The ability to enumerate users was possible without relevant permissions due to different exception messages depending on whether the user existed or not. It was also possible to enumerate users by using a timing attack, by comparing time elapsed when authenticating an existing user and authenticating a non-existing user.

Resolution
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We now ensure that 403s are returned whether the user exists or not if the password is invalid or if the user does not exist.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/2a581d22cc621b33d5464ed65c4bc2057f72f011) for branch 3.4.

Credits
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I would like to thank James Isaac and Mathias Brodala for reporting the issue and Robin Chalas for fixing the issue.

Cross-Site Request Forgery (CSRF)
The current implementation of CSRF protection in Symfony does not use different tokens for HTTP and HTTPS.