An issue was discovered in TCG Accelerator in QEMU 4.2.0, allows local attackers to execute arbitrary code, escalate privileges, and cause a denial of service (DoS). Note: This is disputed as a bug and not a valid security issue by multiple third parties.

QEMU 4.2.0 has a use-after-free in hw/net/e1000e_core.c because a guest OS user can trigger an e1000e packet with the data's address set to the e1000e's MMIO address.

ati-vga in hw/display/ati.c in QEMU 4.2.0 allows guest OS users to trigger infinite recursion via a crafted mm_index value during an ati_mm_read or ati_mm_write call.

address_space_map in exec.c in QEMU 4.2.0 can trigger a NULL pointer dereference related to BounceBuffer.

hw/net/tulip.c in QEMU 4.2.0 has a buffer overflow during the copying of tx/rx buffers because the frame size is not validated against the r/w data length.

tftp.c in libslirp 4.1.0, as used in QEMU 4.2.0, does not prevent ..\ directory traversal on Windows.

tcp_emu in tcp_subr.c in libslirp 4.1.0, as used in QEMU 4.2.0, mismanages memory, as demonstrated by IRC DCC commands in EMU_IRC. This can cause a heap-based buffer overflow or other out-of-bounds access which can lead to a DoS or potential execute arbitrary code.

The qdisk PV disk backend in qemu-xen in Xen 4.2.x and 4.3.x before 4.3.1, and qemu 1.1 and other versions, allows local HVM guests to cause a denial of service (domain grant reference consumption) via unspecified vectors.