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Fencer Vulns
high 7.1

CVE-2026-23555 json

Xenstored DoS by unprivileged domain

published 2026-03-23 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-14383

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

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.

Patch / fix

  • xen Debian 13 4.20.3+127-gc42374a105-0+deb13u1
  • xen Debian 14 4.20.3+127-gc42374a105-1

debian advisories DEBIAN-CVE-2026-23555

  • xen SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 4.20.2_08-150700.3.28.1
  • xen SLES for SAP 15 SP6, SLES 15 SP6-LTSS, openSUSE Leap 15.6 4.18.5_12-150600.3.40.1

suse advisories SUSE-SU-2026:1093-1SUSE-SU-2026:0908-1

  • xen openSUSE Tumbleweed 4.21.1_02-1.1

opensuse advisories openSUSE-SU-2026:10457-1

  • xen Alpine 3.20 4.18.5-r5
  • xen Alpine 3.21 4.19.4-r2
  • xen Alpine 3.23, Alpine 3.22 4.20.2-r2
  • xen Alpine 3.24 4.21.0-r3

alpine advisories ALPINE-CVE-2026-23555

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-23555 updated cvss 6.5

Xen: Xenstored: Denial of Service via illegal Xenstore node path

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Affected products

  • Xen Xen

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.