Executive Summary

CVE-2025-8860 is an information disclosure vulnerability in the QEMU-KVM component related to UEFI variable handling.

When a guest writes to the UEFI_VARS_REG_BUFFER_SIZE register, the `uefi_vars_write` callback function allocates a heap buffer but does not zero out the memory. This leaves the buffer filled with residual data from previous allocations.

Later, when the guest reads from the UEFI_VARS_REG_PIO_BUFFER_TRANSFER register, the `uefi_vars_read` callback returns this leftover data, which may include sensitive metadata or other process memory contents.

This results in an information disclosure vulnerability, potentially exposing sensitive information from the host or other processes.

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Impact Analysis

This vulnerability can lead to unintended information disclosure.

Specifically, sensitive metadata or other process memory from previous allocations may be exposed to a guest virtual machine running on QEMU-KVM with UEFI variable support.

An attacker with access to the guest could potentially read sensitive information from the host or other processes, which could be leveraged for further attacks or data breaches.

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Compliance Impact

I don't know

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Detection Guidance

I don't know

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Mitigation Strategies

To mitigate this vulnerability, you should update QEMU-KVM to a version that includes the upstream fix which ensures proper memory initialization during buffer allocation.

This fix prevents the information disclosure by zeroing out the heap buffer before use, eliminating residual data exposure.

Ensure your Linux operating system running QEMU-KVM with UEFI variable support is patched accordingly.

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