Xen: domctl Lock Open to Abuse (XSA-492)

medium Nessus Plugin ID 320869

Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

To create and manage guests, domctl operations are used by the control domain, a possible Xenstore domain, or by a domain controlling a particular guest. Some of these operations may not be executed in parallel, so a system-wide lock is used. The way that lock is acquired is, however, not providing any fairness. This is CVE-2026-42489. Furthermore, with XSM/Flask in use, the lock acquire will, for some operations, occur ahead of any permission checking. This is CVE-2026-42490. A less privileged entity may stall an equally or more privileged entity, potentially leading to a Denial of Service (DoS) of up to the entire host.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Apply the appropriate patch according to the vendor advisory.

Plugin Details

Severity: Medium

ID: 320869

File Name: xen_server_XSA-492.nasl

Version: 1.1

Type: Local

Family: Misc.

Published: 6/12/2026

Updated: 6/12/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C

CVSS Score Source: CVE-2026-42489

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: installed_sw/Xen Hypervisor, Settings/ParanoidReport

Patch Publication Date: 6/9/2026

Vulnerability Publication Date: 6/9/2026

Reference Information

CVE: CVE-2026-42489, CVE-2026-42490

IAVB: 2026-B-0069

Detections

Analytics