QEMU 0.9.0 does not properly handle changes to removable media, which allows guest OS users to read arbitrary files on the host OS by using the diskformat: parameter in the -usbdevice option to modify the disk-image header to identify a different format, a related issue to CVE-2008-2004.
Quote from http://patchwork.ozlabs.org/patch/35412/: Commit 9ef1d4c7c7aca1cd436612b6ca785b726ffb8ed8 introduced a typo in initialization.
arch/x86/ia32/ia32entry.S in the Linux kernel before 2.6.31.4 on the x8664 platform does not clear certain kernel registers before a return to user mode, which allows local users to read register values from an earlier process by switching an ia32 process to 64-bit mode.