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CVE-2026-23555

Xenstored DoS by unprivileged domain

7.1 HighFix available

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.18%Up 0.2 points since Mar 23, 2026
90%50%10%1%

What each source reports

NVD Score used 7.1

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
CVE-2026-23555
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness
CWE-617
Updated
2026-11-02
CVE List 7.1

Xenstored DoS by unprivileged domain

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
CVE-2026-23555
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness
CWE-617
Updated
2026-11-02
EUVDEUVD-2026-14383 7.1

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
EUVD-2026-14383
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-hv7f-mhvh-6mf6 7.1

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local...

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
GHSA-hv7f-mhvh-6mf6
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness
CWE-617
Updated
2026-11-02
OSVALPINE-CVE-2026-23555 7.1

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
ALPINE-CVE-2026-23555
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2026-23555 7.1

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path. Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
DEBIAN-CVE-2026-23555
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Updated
2026-11-02
Show 4 moreShow less
OSVUBUNTU-CVE-2026-23555 7.1

Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path. Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.

Record
UBUNTU-CVE-2026-23555
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2026:10457-1 No score

xen-4.21.1_02-1.1 on GA media

These are all security issues fixed in the xen-4.21.1_02-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:10457-1
Updated
2026-11-02
OSVSUSE-SU-2026:0908-1 No score

Security update for xen

This update for xen fixes the following issues:

  • CVE-2026-23554: xen: Use after free of paging structures in EPT (bsc#1259247, XSA-480)
  • CVE-2026-23555: xen: Xenstored DoS by unprivileged domain (bsc#1259248, XSA-481)
Record
SUSE-SU-2026:0908-1
Updated
2026-11-02
OSVSUSE-SU-2026:1093-1 No score

Security update for xen

This update for xen fixes the following issues:

  • CVE-2026-23554: xen: Use after free of paging structures in EPT (bsc#1259247, XSA-480)
  • CVE-2026-23555: xen: Xenstored DoS by unprivileged domain (bsc#1259248, XSA-481)
Record
SUSE-SU-2026:1093-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
xen
Alpine:v3.20
 4.18.0 up to 4.18.5-r5
4.18.5-r5
xen
Alpine:v3.21
 4.18.0 up to 4.19.4-r2
4.19.4-r2
xen
Alpine:v3.22
 4.18.0 up to 4.20.2-r2
4.20.2-r2
xen
Alpine:v3.23
 4.18.0 up to 4.20.2-r2
4.20.2-r2
xen
Alpine:v3.24
 4.18.0 up to 4.21.0-r3
4.21.0-r3
xen
Debian:13
 before 4.20.3+127-gc42374a105-0+deb13u1, plus listed versions
4.20.0+68-g35cb38b222-14.20.2+37-g61ff35323e-0+deb13u14.20.2+37-g61ff35323e-14.20.2+7-g1badcf5035-0+deb13u14.20.2+7-g1badcf5035-14.20.2+7-g1badcf5035-2
4.20.3+127-gc42374a105-0+deb13u1
xen
Debian:14
 before 4.20.3+127-gc42374a105-1, plus listed versions
4.20.0+68-g35cb38b222-14.20.2+37-g61ff35323e-14.20.2+7-g1badcf5035-14.20.2+7-g1badcf5035-2
4.20.3+127-gc42374a105-1
xen
SUSE:Linux Enterprise Server 15 SP6-LTSS
From an advisory covering 2 CVEs
 before 4.18.5_12-150600.3.40.1
4.18.5_12-150600.3.40.1
xen
SUSE:Linux Enterprise Server for SAP Applications 15 SP6
From an advisory covering 2 CVEs
 before 4.18.5_12-150600.3.40.1
4.18.5_12-150600.3.40.1
xen
openSUSE:Leap 15.6
From an advisory covering 2 CVEs
 before 4.18.5_12-150600.3.40.1
4.18.5_12-150600.3.40.1
Show 11 moreShow less
Affected packages
PackageAffectedFixed
xen
SUSE:Linux Enterprise Module for Basesystem 15 SP7
From an advisory covering 2 CVEs
 before 4.20.2_08-150700.3.28.1
4.20.2_08-150700.3.28.1
xen
SUSE:Linux Enterprise Module for Server Applications 15 SP7
From an advisory covering 2 CVEs
 before 4.20.2_08-150700.3.28.1
4.20.2_08-150700.3.28.1
xen
Ubuntu:16.04:LTS
 All versions, plus listed versions
4.5.1-0ubuntu14.5.1-0ubuntu24.6.0-1ubuntu14.6.0-1ubuntu24.6.0-1ubuntu4
Show 7 moreShow less
4.6.0-1ubuntu4.14.6.0-1ubuntu4.24.6.0-1ubuntu4.34.6.5-0ubuntu14.6.5-0ubuntu1.14.6.5-0ubuntu1.24.6.5-0ubuntu1.4
 None known
xen
Ubuntu:18.04:LTS
 All versions, plus listed versions
4.9.0-0ubuntu34.9.0-0ubuntu44.9.2-0ubuntu1
 None known
xen
Ubuntu:20.04:LTS
 All versions, plus listed versions
4.9.2-0ubuntu24.9.2-0ubuntu64.9.2-0ubuntu74.11.3+24-g14b62ab3e5-1ubuntu14.11.3+24-g14b62ab3e5-1ubuntu24.11.3+24-g14b62ab3e5-1ubuntu2.24.11.3+24-g14b62ab3e5-1ubuntu2.3
 None known
xen
Ubuntu:22.04:LTS
 All versions, plus listed versions
4.11.4+24-gddaaccbbab-1ubuntu24.16.0-1~ubuntu24.16.0-1~ubuntu2.1
 None known
xen
Ubuntu:24.04:LTS
 All versions, plus listed versions
4.17.2-14.17.2+55-g0b56bed864-14.17.2+76-ge1f9cb16e2-14.17.2+76-ge1f9cb16e2-1ubuntu14.17.3+10-g091466ba55-14.17.3+10-g091466ba55-1.1ubuntu24.17.3+10-g091466ba55-1.1ubuntu3
 None known
xen
Ubuntu:25.10
 All versions, plus listed versions
4.20.0-1ubuntu14.20.0+68-g35cb38b222-1
 None known
xen
Ubuntu:26.10
 All versions, plus listed versions
4.20.2+7-g1badcf5035-2build24.20.2+37-g61ff35323e-1ubuntu14.20.3+127-gc42374a105-1
 None known
xen
Ubuntu:26.04:LTS
 All versions, plus listed versions
4.20.0+68-g35cb38b222-14.20.2+7-g1badcf5035-24.20.2+7-g1badcf5035-2build2
 None known
xen
openSUSE:Tumbleweed
From an advisory covering 2 CVEs
 before 4.21.1_02-1.1
4.21.1_02-1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-23555 is a high vulnerability (CVSS 7.1) in Xen, published March 17, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 8th percentile. Fixed in xen 4.18.5-r5.

References

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