CWE-416

A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the descriptor’s address belongs to the non direct access region, due to num_buffers being set after the virtqueue elem has been unmapped. A malicious guest could use this flaw to crash QEMU, resulting in a denial of service condition, or potentially execute code on the host with the privileges of the QEMU process.

A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU. EHCI does not verify if the Buffer Pointer overlaps with its MMIO region when it transfers the USB packets. Crafted content may be written to the controller’s registers and trigger undesirable actions (such as reset) while the device is still transferring packets. This can ultimately lead to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition, or potentially execute arbitrary code within the context of the QEMU process on the host. This flaw affects QEMU versions before 7.0.0.

In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections via a mechanism called ‘association groups’. These handles can reference connections to our sam.ldb database. However while the database was correctly shared, the user credentials state was only pointed at, and when one connection within that association group ended, the database would be left pointing at an invalid ‘struct session_info’. The most likely outcome here is a crash, but it is possible that the use-after-free could instead allow different user state to be pointed at and this might allow more privileged access.

GCC c++filt v2.26 was discovered to contain a use-after-free vulnerability via the component cplus-dem.c.