Citrix Systems XenServer und Xen: Schwachstelle ermöglicht Offenlegung von Informationen
WID-SEC-2026-0229 · first 28.01.2026 · updated 05.10.2026 · CVSS 3,3
What it is about
Citrix XenServer ist eine Lösung für das Management, die Konfiguration und den Betrieb virtueller Maschinen auf Servern. Xen ist ein Virtueller-Maschinen-Monitor (VMM), der Hardware (x86, IA-64, PowerPC) für die darauf laufenden Systeme (Domains) paravirtualisiert. Ein lokaler Angreifer kann eine Schwachstelle in Citrix Systems XenServer und Xen ausnutzen, um Informationen offenzulegen.
Under what conditions?
Only with access to the device or an account on it. Often the second step after a phishing email.
What can happen in the worst case
An attacker could use the vulnerability to
- Informationen offenzulegen
Am I affected?
Affected according to the BSI:
- Debian Linux
- Fedora Linux
- SUSE Linux
- SUSE openSUSE
- Citrix Systems XenServer 8.4
- Open Source Xen <4.18.x
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Open Source Xen 4.18.x
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- Xen Security Advisory 479 vom 2026-01-27 xenbits.xen.org
- Citrix XenServer Security Update vom 2026-01-27 support.citrix.com
- SUSE Security Update SUSE-SU-2026:0303-1 vom 2026-01-28 lists.suse.com
- SUSE Security Update SUSE-SU-2026:0304-1 vom 2026-01-28 lists.suse.com
- SUSE Security Update SUSE-SU-2026:0306-1 vom 2026-01-28 lists.suse.com
- SUSE Security Update SUSE-SU-2026:0328-1 vom 2026-01-29 lists.suse.com
- SUSE Security Update SUSE-SU-2026:0329-1 vom 2026-01-29 lists.suse.com
- Fedora Security Advisory FEDORA-2026-844012D662 vom 2026-01-29 bodhi.fedoraproject.org
- Fedora Security Advisory FEDORA-2026-E39149A8A0 vom 2026-01-29 bodhi.fedoraproject.org
- openSUSE Security Update OPENSUSE-SU-2026:10118-1 vom 2026-01-31 lists.opensuse.org
- SUSE Security Update SUSE-SU-2026:0394-1 vom 2026-02-05 lists.suse.com
- Debian Security Advisory DLA-4818 vom 2026-10-04 lists.debian.org
CVE: CVE-2026-23553
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.