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XenOperating system

CVE-2026-23554

HIGH · 7.8 CVSS v3.1 Published 2026-03-23
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
80/100
Remediation priority · High
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
XenOperating system
Affected:>= 4.17

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch xenbits.xenproject.org →
Recommended fix High confidence

Xen version containing XSA-480 fix (check xenbits.xenproject.org/xsa/advisory-480.html for exact version number)

  1. 1. Identify the current Xen version running on the system using `xl version` or `xm version`
  2. 2. Check the Xen Security Advisory XSA-480 at https://xenbits.xenproject.org/xsa/advisory-480.html for the specific fixed version
  3. 3. Plan maintenance window as hypervisor upgrade requires host reboot
  4. 4. Back up all VM configurations (e.g., `xl list > /backup/vm_list.txt` and copy /etc/xen/*.cfg files)
  5. 5. Upgrade Xen packages to the fixed version using distribution package manager (e.g., `apt-get update && apt-get install xen-hypervisor` or `yum update xen` depending on distribution)
  6. 6. Verify the new Xen version matches the fixed release noted in XSA-480
  7. 7. Reboot the host to load the updated hypervisor
  8. 8. After reboot, verify all VMs start correctly and run normally
Caveat Hypervisor upgrade requires host reboot, causing VM downtime; ensure HA/DRS is configured or plan controlled maintenance window

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-23554 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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