Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Starting in versions 5.4.21 and 6.2.7 and prior to versions 5.4.31 and 6.3.8, SessionStrategyListener does not migrate the session after every successful login. It does so only in case the logged in user changes by means of checking the user identifier. In some use cases, the user identifier doesnt change between the verification phase and the successful login, while the token itself changes from one type (partially-authenticated) to another (fully-authenticated). When this happens, the session id should be regenerated to prevent possible session fixations, which is not the case at the moment. As of versions 5.4.31 and 6.3.8, Symfony now checks the type of the token in addition to the user identifier before deciding whether the session id should be regenerated.
Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Symfony | Sensiolabs | 5.4.21 (including) | 5.4.31 (excluding) |
| Symfony | Sensiolabs | 6.2.7 (including) | 6.3.8 (excluding) |
| Symfony | Ubuntu | bionic | * |
| Symfony | Ubuntu | lunar | * |
| Symfony | Ubuntu | mantic | * |
| Symfony | Ubuntu | trusty | * |
| Symfony | Ubuntu | upstream | * |
| Symfony | Ubuntu | xenial | * |
Such a scenario is commonly observed when:
In the generic exploit of session fixation vulnerabilities, an attacker creates a new session on a web application and records the associated session identifier. The attacker then causes the victim to associate, and possibly authenticate, against the server using that session identifier, giving the attacker access to the user’s account through the active session.