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CVE-2025-58151

varstored: TOCTOU issues with mapped guest memory

9.4 Critical

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.14%Unchanged since Jul 10, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.4

varstored: TOCTOU issues with mapped guest memory

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.

Record
CVE-2025-58151
CVSS 4.0
9.4 CriticalCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Weakness
CWE-367
Updated
2026-11-02
EUVDEUVD-2025-210447 9.4

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.

Record
EUVD-2025-210447
CVSS 4.0
9.4 CriticalCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-78gx-8v3c-jqwc 9.4

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a...

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.

Record
GHSA-78gx-8v3c-jqwc
CVSS 4.0
9.4 CriticalCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-367
Updated
2026-11-02
NVD 9.4

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.

Record
CVE-2025-58151
CVSS 4.0
9.4 CriticalCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-367
Updated
2026-11-02
OSVALPINE-CVE-2025-58151 9.4

varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.

Record
ALPINE-CVE-2025-58151
CVSS 4.0
9.4 CriticalCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02

Affected products

History

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

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

In short

CVE-2025-58151 is a critical vulnerability (CVSS 9.4) in Xen Varstored, published July 9, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.14%, the 3rd percentile. No source names a fixed version.

References

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