CVE-2026-23560
Deferred Deferred - Pending Action

Privilege Escalation in XenServer XAPI

Publication date: 2026-07-09

Last updated on: 2026-07-09

Assigner: Xen Project

Description
[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] XAPI can configure different users with different roles, using Role Based Access Control. For more details, see: https://docs.xenserver.com/en-us/xencenter/current-release/rbac-overview.html#rbac-roles The pool-admin role is fully privileged. Notably, users with this role can also SSH into the host as root. The other administrator roles are pool-operator, vm-power-admin and vm-admin, each of which are authorised to configure and manage various aspects of the system. Some settings are inadequately restricted, and can be set by a lower privilege of administrator than expected. * CVE-2026-23559: A vm-admin can set VBD.other_config:backend-local and turn arbitrary files in dom0 into VDIs (virtual disks) and give said disks to a VM they control. This is an arbitrary read and/or modify of files in dom0. * CVE-2026-23560: A vm-admin can set VM.other-config:is_system_domain and mark a VM as a system domain. System domains are ignored and left running during certain other host/pool operations, and may be hidden from view in tooling. * CVE-2026-23561: A vm-admin can set VM.other_config:storage_driver_domain and mark a VM as the storage domain for a particular host storage connection (PBD). Shutting down the VM can cause the PBD to be erroneously marked as unplugged when it is not. * CVE-2026-23562: Configuration of PCI passthrough is normally restricted to the pool-admin role. However one API was missing this check, allowing a vm-admin access to unintended host hardware. * CVE-2026-42486: A vm-admin can set the VM.platform:hvm_serial parameter, which should be restricted to the pool-admin role, as it can allow arbitrary dom0 file write.

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Meta Information

Published
2026-07-09
Last Modified
2026-07-09
Generated
2026-07-15
AI Q&A
2026-07-09
EPSS Evaluated
2026-07-14
NVD
CVE-2026-23560
EUVD
EUVD-2026-42603

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
xen xapi *
xen server *
xen xapi 26.12.0
xen xapi 26.1.11

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-250 The product performs an operation at a privilege level that is higher than the minimum level required, which creates new weaknesses or amplifies the consequences of other weaknesses.

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Executive Summary

This vulnerability (CVE-2026-23560) involves the vm-admin role in XAPI being able to set the VM.other-config:is_system_domain parameter to mark a virtual machine (VM) as a system domain.

System domains are special VMs that are ignored and left running during certain host or pool operations and may be hidden from view in management tools.

Because a vm-admin can mark a VM as a system domain, they can potentially bypass expected restrictions and controls that apply to normal VMs, leading to unauthorized persistence or concealment of VMs during administrative operations.

Impact Analysis

This vulnerability allows a vm-admin, who normally has limited privileges compared to a pool-admin, to mark a VM as a system domain.

Since system domains are ignored during certain host or pool operations and may be hidden from management tools, this can lead to unauthorized VMs running undetected.

This could result in unauthorized persistence of VMs, potential evasion of security controls, and difficulties in managing or auditing the virtual environment.

Compliance Impact

The vulnerability allows lower-privileged administrators (such as vm-admins) to escalate their privileges to pool-admin level, granting full system access including root SSH access. This unauthorized privilege escalation and potential arbitrary file read/write in the dom0 system can lead to unauthorized access and modification of sensitive data.

Such unauthorized access and control over system resources can compromise the confidentiality, integrity, and availability of data, which are critical requirements under common standards and regulations like GDPR and HIPAA.

Therefore, if exploited, this vulnerability could lead to non-compliance with these regulations due to potential data breaches, unauthorized data manipulation, and failure to enforce proper access controls.

Detection Guidance

Detection of this vulnerability involves identifying if any users with the vm-admin role have set specific VM parameters that exploit the vulnerability, such as VM.other-config:is_system_domain.

Since the vulnerability allows a vm-admin to mark a VM as a system domain, which may be hidden from view in tooling and remain running during certain operations, checking VM configurations for this setting is key.

Commands to detect this could include querying the VM configurations via XAPI or XenServer management tools to list VMs and inspect their other-config parameters for the is_system_domain flag.

  • Use `xe vm-list params=other-config` to list VMs and their other-config parameters.
  • Filter the output to find VMs where `other-config:is_system_domain=true`.
  • Review user roles assigned in XAPI to identify any vm-admin users who might have made such changes.
Mitigation Strategies

Immediate mitigation involves disabling or removing users assigned the vulnerable roles such as vm-admin, which can exploit this vulnerability to escalate privileges.

Applying patches released in XAPI versions v26.12.0 and v26.1.11 is critical to fix the underlying RBAC issues.

Review and restrict role assignments to ensure only trusted administrators have elevated privileges.

  • Disable or remove vm-admin users until patches are applied.
  • Upgrade XAPI to version v26.12.0 or later, or v26.1.11 or later.
  • Audit existing VM configurations for unauthorized settings like is_system_domain and revert them if found.

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