Race condition in Xen - CVE-2026-42487
Published: June 9, 2026
Vulnerability identifier: #VU134006
CSH Severity: Low
CVSS v4: 7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42487
CWE-ID: CWE-362
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper synchronization in the I/O port mapping list traversal logic when handling guest I/O port accesses. A remote user can modify I/O port mappings during traversal to cause a denial of service.
Only x86 systems are vulnerable. Exploitation requires control of an HVM guest device model running in a stub domain or de-privileged in Dom0.
Affected software
Xen
Debian Linux
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
Basesystem Module
Server Applications Module
openSUSE Leap
Fedora
xen-tools-debuginfo
xen-libs
xen-tools-domU
xen-debugsource
xen-tools-domU-debuginfo
xen
xen-libs-32bit
xen-libs-debuginfo-32bit
xen-devel
xen-libs-debuginfo
xen-doc-html
xen-tools
xen-libs-64bit-debuginfo
xen-libs-64bit
xen-libs-32bit-debuginfo
xen-tools-xendomains-wait-disk
xen (Debian package)
Debian Linux
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
Basesystem Module
Server Applications Module
openSUSE Leap
Fedora
xen-tools-debuginfo
xen-libs
xen-tools-domU
xen-debugsource
xen-tools-domU-debuginfo
xen
xen-libs-32bit
xen-libs-debuginfo-32bit
xen-devel
xen-libs-debuginfo
xen-doc-html
xen-tools
xen-libs-64bit-debuginfo
xen-libs-64bit
xen-libs-32bit-debuginfo
xen-tools-xendomains-wait-disk
xen (Debian package)
How to mitigate CVE-2026-42487
Install security update from vendor's website.
xen-tools-debuginfo - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-tools-domU - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-debugsource - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-tools-domU-debuginfo - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs-32bit - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-libs-debuginfo-32bit - update to 4.12.4_70-3.145.1
xen-devel - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs-debuginfo - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-doc-html - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-tools - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs-64bit-debuginfo - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-libs-64bit - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-libs-32bit-debuginfo - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-tools-xendomains-wait-disk - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen (Debian package) - update to 4.20.3+127-gc42374a105-0+deb13u1
xen - addressed in versions 4.20.4-1.fc43, 4.21.1-4.fc44
xen-libs - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-tools-domU - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-debugsource - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-tools-domU-debuginfo - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs-32bit - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-libs-debuginfo-32bit - update to 4.12.4_70-3.145.1
xen-devel - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs-debuginfo - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-doc-html - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-tools - addressed in versions 4.12.4_70-3.145.1, 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen-libs-64bit-debuginfo - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-libs-64bit - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-libs-32bit-debuginfo - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1
xen-tools-xendomains-wait-disk - addressed in versions 4.16.7_10-150400.4.86.2, 4.17.6_12-150500.3.73.1, 4.18.5_18-150600.3.50.1, 4.20.3_06-150700.3.41.1
xen (Debian package) - update to 4.20.3+127-gc42374a105-0+deb13u1
xen - addressed in versions 4.20.4-1.fc43, 4.21.1-4.fc44