IBM WebSphere Portal 6.1.0 through 6.1.0.6 CF27, 6.1.5 through 6.1.5.3 CF27, 7.0 through 7.0.0.2 CF28, and 8.0 before 8.0.0.1 CF12 allows remote authenticated users to cause a denial of service (infinite loop) via a login redirect.