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Fencer Vulns
medium 6.5

CVE-2026-42490 json

domctl lock open to abuse

published 2026-06-18 4 mo ago modified 2026-06-22 4 mo ago also EUVD-2026-37890

cvss
6.5
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 9%
public exploits
0
none known

Summary

[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.]

To create and manage guests, domctl operations are used by the control domain, a possible Xenstore domain, or by a domain controlling a particular guest. Some of these operations may not be executed in parallel, so a system-wide lock is used. The way that lock is acquired is, however, not providing any fairness. This is CVE-2026-42489.

Furthermore, with XSM/Flask in use, the lock acquire will, for some operations, occur ahead of any permission checking. This is CVE-2026-42490.

Patch / fix

  • xen Debian 12 4.17.7-0+deb12u1
  • xen Debian 13 4.20.3+127-gc42374a105-0+deb13u1
  • xen Debian 14 4.20.3+127-gc42374a105-1

debian advisories DEBIAN-CVE-2026-42490

  • xen SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 4.16.7_10-150400.4.86.2
  • xen SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 4.20.3_06-150700.3.41.1
  • xen SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 4.17.6_12-150500.3.73.1
  • xen SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 4.12.4_70-3.145.1
  • xen SLES for SAP 15 SP6, SLES 15 SP6-LTSS 4.18.5_18-150600.3.50.1

suse advisories SUSE-SU-2026:2668-1SUSE-SU-2026:2613-1SUSE-SU-2026:2364-1SUSE-SU-2026:2329-1SUSE-SU-2026:2328-1

  • xen Alpine 3.20 4.18.5-r9
  • xen Alpine 3.21 4.19.5-r4
  • xen Alpine 3.23, Alpine 3.22 4.20.3-r4
  • xen Alpine 3.24 4.21.1-r6

alpine advisories ALPINE-CVE-2026-42490

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-2026-42490 updated cvss 6.5

xen: domctl lock open to abuse

  • 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
4 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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.