CVE-2025-58151varstored: TOCTOU issues with mapped guest memory
Updated under an hour ago ()
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It affects Xen varstored. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 9.4 CRITICAL (v4.0, CNA)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
- Weakness (CWE)
- CWE-367
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- XEN
- NVD analysis
- Deferred
- Record last updated
- Jul 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Xen varstored xen:varstored (from the name) | all versions | CNA record |
References
- 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
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.