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CVE-2025-8860

Qemu-kvm: uefi-vars: information disclosure vulnerability in uefi_vars_write callback

3.3 LowFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.17%Up 0.2 points since Feb 19, 2026
90%50%10%1%

What each source reports

CVE List Score used 3.3

Qemu-kvm: uefi-vars: information disclosure vulnerability in uefi_vars_write callback

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.

Record
CVE-2025-8860
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-212
Updated
2026-11-02
EUVDEUVD-2025-207826 3.3

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.

Record
EUVD-2025-207826
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-xrj7-v4x4-74hr 3.3

A flaw was found in QEMU in the uefi-vars virtual device. When the guest writes to register...

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.

Record
GHSA-xrj7-v4x4-74hr
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-212
Updated
2026-11-02
NVD 3.3

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.

Record
CVE-2025-8860
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-212
Updated
2026-11-02
OSV 3.3

Qemu-kvm: uefi-vars: information disclosure vulnerability in uefi_vars_write callback

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.

Record
CVE-2025-8860
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-212
Updated
2026-11-02
OSVDEBIAN-CVE-2025-8860 3.3

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.

Record
DEBIAN-CVE-2025-8860
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2025-8860 No score

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.

Record
UBUNTU-CVE-2025-8860
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
qemu
Debian:13
before 1:10.0.3+ds-4, plus listed versions
1:10.0.2+ds-21:10.0.2+ds-2+deb13u11:10.0.2+ds-2+deb13u1~bpo12+11:10.0.3+ds-0+deb13u11:10.0.3+ds-11:10.0.3+ds-21:10.0.3+ds-3
1:10.0.3+ds-4
qemu
Debian:14
before 1:10.0.3+ds-4, plus listed versions
1:10.0.2+ds-21:10.0.3+ds-11:10.0.3+ds-21:10.0.3+ds-3
1:10.0.3+ds-4

History

History
RecordedChangedSources
affected
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-8860 is a low vulnerability (CVSS 3.3) in Red Hat Enterprise Linux 10, published August 20, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.17%, the 6th percentile. Fixed in qemu 1:10.0.3+ds-4.

References

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