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Fencer Vulns
high 7.8

CVE-2026-23554 json

Use after free of paging structures in EPT

published 2026-03-23 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-14382

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

The Intel EPT paging code uses an optimization to defer flushing of any cached EPT state until the p2m lock is dropped, so that multiple modifications done under the same locked region only issue a single flush.

Freeing of paging structures however is not deferred until the flushing is done, and can result in freed pages transiently being present in cached state. Such stale entries can point to memory ranges not owned by the guest, thus allowing access to unintended memory regions.

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-2026-23554

  • 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 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 4.17.6_06-150500.3.62.2
  • 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-2026:1092-1SUSE-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-2026-23554

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-2026-23554 updated cvss 7.5

xen: Xen: Information disclosure and potential privilege escalation via use-after-free in EPT paging

  • 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
total
Assessed
7 mo ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Xen Xen

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

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.