Unspecified vulnerability in IBM WebSphere Application Server (WAS) 5.1.x before 5.1.1.19, 6.0.x before 6.0.2.29, and 6.1.x before 6.1.0.19, when Web Server plug-in content buffering is enabled, allows attackers to cause a denial of service (daemon crash) via unknown vectors, related to a mishandling of client read failures in which clients receive many 500 HTTP error responses and backend servers are incorrectly labeled as down.