# CVE-2026-42486: Multiple RBAC issues in XAPI

> A vm-admin can exploit missing authorization checks to write arbitrary files in dom0, leading to privilege escalation.

- **Severity:** Critical 9.4 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jul 2026
- **Updated:** 10 Jul 2026
- **Also known as:** GHSA-f6rw-qmp5-m443

## What is CVE-2026-42486?

CVE-2026-42486 is a critical missing authorization vulnerability in Xen XAPI, published on 9 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-250 (Execution with Unnecessary Privileges)

## Which versions are affected by CVE-2026-42486?


## How do I fix CVE-2026-42486?

No fix has been published for CVE-2026-42486 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-42486 being exploited?

There is no known exploitation of CVE-2026-42486 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42486 and fix it if it is affected.

What it is: CVE-2026-42486 is a critical missing authorization vulnerability in Xen XAPI, published on 9 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-42486 in the wild and no public exploit code.

Affected product: Xen XAPI. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-42486/ (Markdown: https://insights.sbomify.com/CVE-2026-42486/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42486
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42486
- OSV: https://osv.dev/vulnerability/CVE-2026-42486

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42486/
Summaries are generated and may contain mistakes; the official description above is the record.