CVE-2026-23558
Analyzed Analyzed - Analysis Complete
Xen Hypervisor Race Condition in Grant Table Version Change

Publication date: 2026-05-19

Last updated on: 2026-05-19

Assigner: Xen Project

Description
The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.
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Meta Information
Published
2026-05-19
Last Modified
2026-05-19
Generated
2026-06-10
AI Q&A
2026-05-19
EPSS Evaluated
2026-06-08
NVD
CVE-2026-23558
EUVD
EUVD-2026-30928
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
xen xen From 4.0.0 (inc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-362 The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
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Executive Summary

CVE-2026-23558 is a race condition vulnerability in the Xen hypervisor's grant table version 2 implementation. It occurs when an HVM or PVH guest switches from grant table version 2 to version 1 while simultaneously mapping status pages using XENMEM_add_to_physmap. This race condition can cause some status pages to be freed while their mappings are still inserted into the guest's secondary page tables.

Impact Analysis

This vulnerability can lead to privilege escalation, information leaks, or Denial of Service (DoS) that can affect the entire host system running the Xen hypervisor.

Mitigation Strategies

To mitigate the CVE-2026-23558 vulnerability, you should set the hypervisor command line option "gnttab=max-ver:1" or the guest configuration option "max_grant_version=1" for HVM and PVH guests.

Additionally, applying the available patches for Xen versions 4.19.x, 4.18.x, and 4.17.x will resolve the issue.

Compliance Impact

CVE-2026-23558 is a race condition vulnerability in the Xen hypervisor that can lead to privilege escalation, information leaks, or Denial of Service (DoS) affecting the entire host.

Such security issues could potentially impact compliance with standards and regulations like GDPR or HIPAA, which require protection of sensitive data and system integrity.

However, the provided information does not explicitly discuss or analyze the direct impact of this vulnerability on compliance with these or other common standards and regulations.

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