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CWE-250Weakness · CWE-250

CVE-2026-23562

CRITICAL · 9.4 CVSS v4.0 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
99/100
Remediation priority · Urgent
No privileges Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
[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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

XenServer XAPI missing authorization check allows vm-admin role users to access PCI passthrough configuration APIs normally restricted to pool-admin role, enabling unintended host hardware access.

MitigationImplement proper RBAC enforcement for PCI passthrough API calls to verify pool-admin role before allowing configuration changes.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

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:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify XenServer and XAPI version
    Run 'xe host-list' and 'xe version' commands or check /etc/xensource/version to determine the installed XenServer and XAPI version
    Affected if Installed version falls within the affected range but has not been patched
  2. Verify RBAC is configured
    Run 'xe role-list' to list available roles and check if vm-admin and pool-admin roles exist in the environment
    Affected if RBAC is enabled and roles are defined but enforcement is missing for PCI passthrough APIs
  3. Check PCI passthrough is enabled
    Run 'xe pgpu-list' or 'xe gpu-list' to see if PCI passthrough or GPU passthrough is configured on the host
    Affected if PCI passthrough is enabled and any vm-admin user can query or modify the configuration
  4. Test vm-admin role access to PCI passthrough APIs
    Using an account with vm-admin role only, attempt to run commands like 'xe pgpu-param-get' or 'xe vgpu-create' which should be pool-admin only
    Affected if vm-admin role successfully accesses PCI passthrough APIs that should require pool-admin role
  5. Review XAPI audit logs for unauthorized access
    Run 'xe audit-log-list' and search for PCI passthrough API calls made by users with vm-admin role
    Affected if Audit logs show vm-admin users executing pool-admin restricted PCI passthrough operations

If the environment runs a vulnerable XenServer XAPI version and vm-admin role users can access PCI passthrough configuration APIs without proper pool-admin authorization, the environment is affected by CVE-2026-23562.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement proper RBAC enforcement for PCI passthrough API calls to verify pool-admin role before allowing configuration changes.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-23562 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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