The qemu guest agent in Qemu 1.4.1 and earlier, as used by Xen, when started in daemon mode, uses weak permissions for certain files, which allows local users to read and write to these files.
Buffer overflow in the e1000_receive function in the e1000 device driver (hw/e1000.c) in QEMU 1.3.0-rc2 and other versions, when the SBP and LPE flags are disabled, allows remote attackers to cause a denial of service (guest OS crash) and possibly execute arbitrary guest code via a large packet.
Qemu, as used in Xen 4.0, 4.1 and possibly other products, when emulating certain devices with a virtual console backend, allows local OS guest users to gain privileges via a crafted escape VT100 sequence that triggers the overwrite of a "device model's address space."
The bdrv_open function in Qemu 1.0 does not properly handle the failure of the mkstemp function, when in snapshot node, which allows local users to overwrite or read arbitrary files via a symlink attack on an unspecified temporary file.
The pciej_write function in hw/acpi_piix4.c in the PIIX4 Power Management emulation in qemu-kvm does not check if a device is hotpluggable before unplugging the PCI-ISA bridge, which allows privileged guest users to cause a denial of service (guest crash) and possibly execute arbitrary code by sending a crafted value to the 0xae08 (PCI_EJ_BASE) I/O port, which leads to a use-after-free related to "active qemu timers."
Buffer overflow in the virtio subsystem in qemu-kvm 0.14.0 and earlier allows privileged guest users to cause a denial of service (guest crash) or gain privileges via a crafted indirect descriptor related to "virtqueue in and out requests."
The change_process_uid function in os-posix.c in Qemu 0.14.0 and earlier does not properly drop group privileges when the -runas option is used, which allows local guest users to access restricted files on the host.
Multiple heap-based buffer overflows in the virtio-blk driver (hw/virtio-blk.c) in qemu-kvm 0.14.0 allow local guest users to cause a denial of service (guest crash) and possibly gain privileges via a (1) write request to the virtio_blk_handle_write function or (2) read request to the virtio_blk_handle_read function that is not properly aligned.
qemu-kvm before 0.11.0 disables VNC authentication when the password is cleared, which allows remote attackers to bypass authentication and establish VNC sessions.
The virtio_net_bad_features function in hw/virtio-net.c in the virtio-net driver in the Linux kernel before 2.6.26, when used on a guest OS in conjunction with qemu-kvm 0.11.0 or KVM 83, allows remote attackers to cause a denial of service (guest OS crash, and an associated qemu-kvm process exit) by sending a large amount of network traffic to a TCP port on the guest OS, related to a virtio-net whitelist that includes an improper implementation of TCP Segment Offloading (TSO).