Using "" as a pattern in Spring Security configuration for WebFlux creates a mismatch in pattern matching between Spring Security and Spring WebFlux, and the potential for a security bypass.

In Spring Security, versions 5.7.x prior to 5.7.8, versions 5.8.x prior to 5.8.3, and versions 6.0.x prior to 6.0.3, 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. Users of affected versions should apply the following mitigation. 5.7.x users should upgrade to 5.7.8. 5.8.x users should upgrade to 5.8.3. 6.0.x users should upgrade to 6.0.3.

Spring Security versions 5.8 prior to 5.8.5, 6.0 prior to 6.0.5, and 6.1 prior to 6.1.2 could be susceptible to authorization rule misconfiguration if the application uses requestMatchers(String) and multiple servlets, one of them being Spring MVC’s DispatcherServlet. (DispatcherServlet is a Spring MVC component that maps HTTP endpoints to methods on @Controller-annotated classes.)

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

Spring MVC is on the classpath Spring Security is securing more than one servlet in a single application (one of them being Spring MVC’s DispatcherServlet) The application uses requestMatchers(String) to refer to endpoints that are not Spring MVC endpoints

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

The application does not have Spring MVC on the classpath The application secures no servlets other than Spring MVC’s DispatcherServlet The application uses requestMatchers(String) only for Spring MVC endpoints