CVE-2025-8860

A flaw was found in QEMU in the uefi-vars virtual device. When the guest writes to register UEFIVARSREGBUFFERSIZE, the .write callback uefi_vars_write is invoked. The function allocates a heap buffer without zeroing the memory, leaving the buffer filled with residual data from prior allocations. When the guest later reads from register UEFIVARSREGPIOBUFFER_TRANSFER, the .read callback uefi_vars_read returns leftover metadata or other sensitive process memory from the previously allocated buffer, leading to an information disclosure vulnerability.