CVE-2025-58151 Details
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.
A time-of-check to time-of-use (TOCTOU) vulnerability has been identified in the varstored component of the Xapi toolstack, which manages UEFI variables for virtual machines (VMs). This vulnerability arises from inadequate compiler barriers, leading to TOCTOU issues with data in a shared buffer mapped from OVMF (Open Virtual Machine Firmware) within the VM. Exploitation of this vulnerability allows an attacker with kernel-level access in a UEFI-configured x86 HVM guest to manipulate an index in a jump table, potentially leading to unauthorized code execution and privilege escalation.
Applying the patch available in the Xen Security Advisory XSA-478 resolves this vulnerability. The patch can be applied to the varstored master branch.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 9, 2026CISA-ADP
Assessed Jul 9, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| http://www.openwall.com/lists/oss-security/2026/01/27/2 | CVE | AdvisoryMailing ListRemedy |
| http://xenbits.xen.org/xsa/advisory-478.html | CVE | AdvisoryRemedyVendor |
| https://xenbits.xen.org/xsa/advisory-478.html | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-367 | Time-of-check Time-of-use (TOCTOU) Race Condition | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Xen.org varstored | <= 0 |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 9, 2026 | CVE Modified | CISA-ADP |
| Jul 9, 2026 | New CVE Received | [email protected] |
| Jul 9, 2026 | CVE Modified | CVE |