Input validation error in Xen - CVE-2026-42494
Published: July 29, 2026
Vulnerability identifier: #VU140027
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42494
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to escalate privileges.
The vulnerability exists due to an out-of-bounds read or write in libfsimage's iso9660 directory record loop when parsing a crafted iso9660 filesystem image. A remote user can provide a crafted disk image to pygrub to escalate privileges.
Exploitation requires a guest to use the pygrub bootloader.
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 15
SUSE Linux Enterprise Server for SAP Applications 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 High Performance Computing 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
Basesystem Module
Server Applications Module
openSUSE Leap
Fedora
xen-debugsource
xen-tools-domU
xen-libs
xen-devel
xen-libs-debuginfo-32bit
xen-libs-debuginfo
xen-libs-32bit
xen-tools-domU-debuginfo
xen-tools-debuginfo
xen-tools
xen-doc-html
xen
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 15
SUSE Linux Enterprise Server for SAP Applications 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 High Performance Computing 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
Basesystem Module
Server Applications Module
openSUSE Leap
Fedora
xen-debugsource
xen-tools-domU
xen-libs
xen-devel
xen-libs-debuginfo-32bit
xen-libs-debuginfo
xen-libs-32bit
xen-tools-domU-debuginfo
xen-tools-debuginfo
xen-tools
xen-doc-html
xen
xen-libs-32bit-debuginfo
xen-tools-xendomains-wait-disk
xen (Debian package)
How to mitigate CVE-2026-42494
Install security update from vendor's website.
xen-debugsource - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-tools-domU - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-devel - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs-debuginfo-32bit - update to 4.12.4_72-3.148.4
xen-libs-debuginfo - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs-32bit - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3
xen-tools-domU-debuginfo - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-tools-debuginfo - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-tools - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-doc-html - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3
xen - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs-32bit-debuginfo - addressed in versions 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3
xen-tools-xendomains-wait-disk - addressed in versions 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen (Debian package) - update to 4.20.3+127-gc42374a105-0+deb13u1
xen - addressed in versions 4.20.4-1.fc43, 4.21.2-1.fc44
xen-tools-domU - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-devel - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs-debuginfo-32bit - update to 4.12.4_72-3.148.4
xen-libs-debuginfo - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs-32bit - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3
xen-tools-domU-debuginfo - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-tools-debuginfo - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-tools - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-doc-html - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3
xen - addressed in versions 4.12.4_72-3.148.4, 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen-libs-32bit-debuginfo - addressed in versions 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3
xen-tools-xendomains-wait-disk - addressed in versions 4.16.7_12-150400.4.89.3, 4.17.6_14-150500.3.76.3, 4.18.5_20-150600.3.53.3, 4.20.4_04-150700.3.46.1
xen (Debian package) - update to 4.20.3+127-gc42374a105-0+deb13u1
xen - addressed in versions 4.20.4-1.fc43, 4.21.2-1.fc44