A flaw was found in the QXL display device emulation in QEMU. A double fetch of guest controlled values `cursor->header.width` and `cursor->header.height` can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer overflow. A malicious privileged guest user could use this flaw to crash the QEMU process on the host or potentially execute arbitrary code within the context of the QEMU process.

A flaw was found in the QXL display device emulation in QEMU. An integer overflow in the cursor_alloc() function can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer overflow. This flaw allows a malicious privileged guest user to crash the QEMU process on the host or potentially execute arbitrary code within the context of the QEMU process.

It was discovered that the update for the virt:rhel module in the RHSA-2020:4676 (https://access.redhat.com/errata/RHSA-2020:4676) erratum released as part of Red Hat Enterprise Linux 8.3 failed to include the fix for the qemu-kvm component issue CVE-2020-10756, which was previously corrected in virt:rhel/qemu-kvm via erratum RHSA-2020:4059 (https://access.redhat.com/errata/RHSA-2020:4059). CVE-2021-20295 was assigned to that Red Hat specific security regression. For more details about the original security issue CVE-2020-10756, refer to bug 1835986 or the CVE page: https://access.redhat.com/security/cve/CVE-2020-10756.

A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device. This flaw allows a crafted guest driver to execute HW commands when shared buffers are not yet allocated, potentially leading to a use-after-free condition.

A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device. The issue occurs while handling a "PVRDMA_CMD_CREATE_MR" command due to improper memory remapping (mremap). This flaw allows a malicious guest to crash the QEMU process on the host. The highest threat from this vulnerability is to system availability.

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 flaw was found in the vhost-vsock device of QEMU. In case of error, an invalid element was not detached from the virtqueue before freeing its memory, leading to memory leakage and other unexpected results. Affected QEMU versions <= 6.2.0.

A flaw was found in the virtio-net device of QEMU. This flaw was inadvertently introduced with the fix for CVE-2021-3748, which forgot to unmap the cached virtqueue elements on error, leading to memory leakage and other unexpected results. Affected QEMU version: 6.2.0.

An out-of-bounds memory access flaw was found in the ATI VGA device emulation of QEMU. This flaw occurs in the ati_2d_blt() routine while handling MMIO write operations when the guest provides invalid values for the destination display parameters. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service.

A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device in versions prior to 6.1.0. The issue occurs while handling a "PVRDMA_REG_DSRHIGH" write from the guest and may result in a crash of QEMU or cause undefined behavior due to the access of an uninitialized pointer. The highest threat from this vulnerability is to system availability.