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, 8.0 through 8.0.0.1 CF14, and 8.5.0 before CF03 provides different web-server error codes depending on whether a requested file exists, which allows remote attackers to determine the validity of filenames via a series of requests.