A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single large transfer request to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper validation. Since the total size is not bounded a malicious guest could use this flaw to influence the array length and cause the QEMU process to perform an excessive allocation on the stack resulting in a denial of service.

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