The class file parser in IBM Java before 1.4.2 SR13 FP9, as used in IBM Runtimes for Java Technology 5.0.0 before SR13 and 6.0.0 before SR10, allows remote authenticated users to cause a denial of service (JVM segmentation fault, and possibly memory consumption or an infinite loop) via a crafted attribute length field in a class file, which triggers a buffer over-read.