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CVE-2026-23554· NVD / CVE Program· CNA XEN

Use after free of paging structures in EPT

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: xen (Alpine:v3.20) 4.18.5-r5; xen (Alpine:v3.21) 4.19.4-r2; xen (Alpine:v3.22) 4.20.2-r2.

Low priority for now. Upgrade to xen (Alpine:v3.20) 4.18.5-r5; xen (Alpine:v3.21) 4.19.4-r2; xen (Alpine:v3.22) 4.20.2-r2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

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.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Mar 23, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-23554

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
xenxen

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • xen xen4.17 and later

Versions reported by the vendor

Affected version ranges reported by the assigning authority (XEN). Independent of NVD's CPE analysis and usually ahead of it.

  • Xen Xen

    • consult Xen advisory XSA-480unknown

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.20xenfrom 4.17 · before 4.18.5-r54.18.5-r5
Alpine:v3.21xenfrom 4.17 · before 4.19.4-r24.19.4-r2
Alpine:v3.22xenfrom 4.17 · before 4.20.2-r24.20.2-r2
Alpine:v3.24xenfrom 4.17 · before 4.21.0-r34.21.0-r3
Debian:12xenbefore 4.17.7-0+deb12u14.17.7-0+deb12u1
Debian:13xenbefore 4.20.3+127-gc42374a105-0+deb13u14.20.3+127-gc42374a105-0+deb13u1
Debian:14xenbefore 4.20.3+127-gc42374a105-14.20.3+127-gc42374a105-1
openSUSE:Tumbleweedxenbefore 4.21.1_02-1.14.21.1_02-1.1
SUSE:Linux Enterprise Micro 5.5xenbefore 4.17.6_06-150500.3.62.24.17.6_06-150500.3.62.2
SUSE:Linux Enterprise Module for Basesystem 15 SP7xenbefore 4.20.2_08-150700.3.28.14.20.2_08-150700.3.28.1
SUSE:Linux Enterprise Server 15 SP6-LTSSxenbefore 4.18.5_12-150600.3.40.14.18.5_12-150600.3.40.1
SUSE:Linux Enterprise Server 15 SP6-LTSSxenbefore 4.18.5_12-150600.3.40.14.18.5_12-150600.3.40.1

Same product

xen: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-10921The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and GNTMAP_host_map mapping, whi
    41Plan
  • CVE-2017-10920The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed by only a GNTMAP_host
    41Plan
  • CVE-2017-10918Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host
    41Plan
  • CVE-2017-10912Xen through 4.8.x mishandles page transfer, which allows guest OS users to obtain privileged host OS access, aka XSA-217.
    41Plan
  • CVE-2015-8104The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a denial of service (host O
    41Plan
  • CVE-2015-5165The C+ mode offload emulation in the RTL8139 network card device model in QEMU, as used in Xen 4.5.x and earlier, allows remote attackers to
    41Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:xen4.18.5-r5 · Alpine:v3.20Package registry (OSV)
debian:xen4.17.7-0+deb12u1 · Debian:12Package registry (OSV)
debian:xen4.20.3+127-gc42374a105-0+deb13u1 · Debian:13Package registry (OSV)
opensuse:xen4.18.5_12-150600.3.40.1 · openSUSE:Leap 15.6Package registry (OSV)
suse:xen4.18.5_12-150600.3.40.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-62428127 days apartgrant-table: type confusion in grant-copy
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

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

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records