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CVE-2026-23554

Use after free of paging structures in EPT

7.8 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.13%Up 0.1 points since Mar 23, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.8

Use after free of paging structures in EPT

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.

Record
CVE-2026-23554
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-367
Updated
2026-11-02
EUVDEUVD-2026-14382 7.8

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.

Record
EUVD-2026-14382
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-h6vw-38xq-3xwx 7.8

The Intel EPT paging code uses an optimization to defer flushing of any cached EPT state until...

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.

Record
GHSA-h6vw-38xq-3xwx
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-367
Updated
2026-11-02
NVD 7.8

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.

Record
CVE-2026-23554
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-367
Updated
2026-11-02
OSVALPINE-CVE-2026-23554 7.8

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.

Record
ALPINE-CVE-2026-23554
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2026-23554 7.8

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.

Record
DEBIAN-CVE-2026-23554
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
Show 6 moreShow less
OSVUBUNTU-CVE-2026-23554 7.8

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.

Record
UBUNTU-CVE-2026-23554
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVMGASA-2026-0068 No score

Updated xen packages fix security vulnerability

Use after free of paging structures in EPT. (CVE-2026-23554)

Record
MGASA-2026-0068
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-2026:1092-1 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)
Record
SUSE-SU-2026:1092-1
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
4.17 up to 4.18.5-r5
4.18.5-r5
xen
Alpine:v3.21
4.17 up to 4.19.4-r2
4.19.4-r2
xen
Alpine:v3.22
4.17 up to 4.20.2-r2
4.20.2-r2
xen
Alpine:v3.23
4.17 up to 4.20.2-r2
4.20.2-r2
xen
Alpine:v3.24
4.17 up to 4.21.0-r3
4.21.0-r3
xen
Debian:12
before 4.17.7-0+deb12u1, plus listed versions
4.17.1+2-gb773c48e36-14.17.2+55-g0b56bed864-14.17.2+76-ge1f9cb16e2-14.17.2+76-ge1f9cb16e2-1~deb12u14.17.2-1
Show 9 moreShow less
4.17.3+10-g091466ba55-14.17.3+10-g091466ba55-1.14.17.3+10-g091466ba55-1.1~exp14.17.3+10-g091466ba55-1.1~exp24.17.3+10-g091466ba55-1~deb12u14.17.3+36-g54dacb5c02-14.17.5+23-ga4e5191dc0-14.17.5+23-ga4e5191dc0-1+deb12u14.17.5+72-g01140da4e8-1
4.17.7-0+deb12u1
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
Mageia:9
before 4.17.5-1.git20251028.3.mga9
4.17.5-1.git20251028.3.mga9
xen
SUSE:Linux Enterprise Server 15 SP6-LTSS
before 4.18.5_12-150600.3.40.1
4.18.5_12-150600.3.40.1
Show 18 moreShow less
Affected packages
PackageAffectedFixed
xen
SUSE:Linux Enterprise Server for SAP Applications 15 SP6
before 4.18.5_12-150600.3.40.1
4.18.5_12-150600.3.40.1
xen
openSUSE:Leap 15.6
before 4.18.5_12-150600.3.40.1
4.18.5_12-150600.3.40.1
xen
SUSE:Linux Enterprise Micro 5.5
before 4.17.6_06-150500.3.62.2
4.17.6_06-150500.3.62.2
xen
SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS
before 4.17.6_06-150500.3.62.2
4.17.6_06-150500.3.62.2
xen
SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS
before 4.17.6_06-150500.3.62.2
4.17.6_06-150500.3.62.2
xen
SUSE:Linux Enterprise Server 15 SP5-LTSS
before 4.17.6_06-150500.3.62.2
4.17.6_06-150500.3.62.2
xen
SUSE:Linux Enterprise Server for SAP Applications 15 SP5
before 4.17.6_06-150500.3.62.2
4.17.6_06-150500.3.62.2
xen
SUSE:Linux Enterprise Module for Basesystem 15 SP7
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
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
before 4.21.1_02-1.1
4.21.1_02-1.1

History

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

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

In short

CVE-2026-23554 is a high vulnerability (CVSS 7.8) in Xen, published March 17, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.13%, the 2nd percentile. Fixed in xen 4.18.5-r5.

References

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