In Spring Security, the logout support does not properly clean the security context if using serialized versions. Additionally, it is not possible to explicitly save an empty security context to the HttpSessionSecurityContextRepository. This vulnerability can keep users authenticated even after they performed logout.

Specifically, an application is vulnerable when any of the following is true:

• You are using the SecurityContextHolderFilter or requireExplicitSave(true) and you are using Spring Security's logout support with serialized sessions (e.g. Spring Session) and invalidateHttpSession(false)
• You are logging users out manually by saving an empty SecurityContext into the HttpSessionSecurityContextRepository
• You have a custom SecurityContextRepository that does not rely on the HttpSession

An application is not vulnerable if any of the following is true:

• You are still using the deprecated SecurityContextPersistenceFilter or requireExplicitSave(false)
• You are using Spring Security's logout support with in-memory sessions.
• You are not saving an empty SecurityContext into the HttpSessionSecurityContextRepository