CVE-2025-8860 Qemu-kvm: uefi-vars: information disclosure vulnerability in uefi_vars_write callback
A guest VM can read uninitialized heap memory from the QEMU UEFI vars device, potentially exposing sensitive host process data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-8860?
CVE-2025-8860 is a low-severity vulnerability in Red Hat Enterprise Linux 10, published on 18 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in QEMU in the uefi-vars virtual device. When the guest writes to register UEFI_VARS_REG_BUFFER_SIZE, 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 UEFI_VARS_REG_PIO_BUFFER_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.
Weakness: CWE-212
Which versions are affected by CVE-2025-8860?
How do I fix CVE-2025-8860?
Apply the vendor's patch.
Is CVE-2025-8860 being exploited?
There is no known exploitation of CVE-2025-8860 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2025-8860, GHSA-xrj7-v4x4-74hr.