CVE-2026-42486
CriticalCVSS 9.4Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
CVE-2026-42486 in XAPI allows a vm-admin user to set the VM.platform:hvm_serial parameter, which should be restricted to the pool-admin role. This enables arbitrary file write in dom0, potentially leading to privilege escalation and system compromise.
Risk Assessment
The organization is at risk of unauthorized file writes in the dom0 domain by lower-privileged administrators, which could result in host takeover, modification of critical configurations, or permanent system damage.
Recommendation
Apply the vendor patch for XAPI immediately and restrict vm-admin role access to trusted users only. Additionally, monitor logs for attempts to set the hvm_serial parameter by unauthorized roles.
Original NVD description (English source)
[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.