[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.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.4): severity, escalated by confirmed exploitation. This CVE's 9.4 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.4 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it