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Vulnerability record · CVE-2025-58151 · published 9 July 2026

CVE-2025-58151: TOCTOU race condition vulnerability

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.

9.4 CVSS 4.0 Critical EPSS 0.14% · top 97.4% CWE-367 · TOCTOU race condition Deferred
9.4CVSS 4.0 base score
0.14%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
9 Jul 2026Last modified by NVD

Description

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.

CVSS: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:

References

LinkTags
https://xenbits.xen.org/xsa/advisory-478.html
http://www.openwall.com/lists/oss-security/2026/01/27/2
http://xenbits.xen.org/xsa/advisory-478.html

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-58151), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.