Affected versions

Symfony versions >=2.0.0, <4.4.50, >= 5.0.0, < 5.4.20, >= 6.0.0, < 6.0.20, >= 6.1.0, < 6.1.12, and >= 6.2.0, < 6.2.6 of the Symfony Security Bundle are affected by this security issue.

The issue has been fixed in Symfony 4.4.50, 5.4.20, 6.0.20, 6.1.12, and 6.2.6. All other versions are not maintained anymore.

Description

When authenticating users, Symfony regenerates the session ID upon login by default, but preserves the rest of session attributes. Because this does not clear CSRF tokens upon login, this might enables same-site attackers to bypass the CSRF protection mechanism by performing an attack similar to a session-fixation.

Resolution

Symfony removes all CSRF tokens from the session on successful login.

The patch for this issue is available here for branch 4.4.

Credits

We would like to thank Marco Squarcina for reporting the issue and Nicolas Grekas for fixing it.