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Citrix Security BulletinsCTX696527

XenServer Security Update for Multiple Issues

An issue that may, in some circumstances, allow a malicious privileged user in a guest VM to compromise the host. This issue has the following identifier:

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HighCVSS not listedHigh severity
Scope

What the vendor says is affected

  • XenServer
  • These issues affect XenServer 8.4. (Note that XenServer 9 is in Public Preview; releases in preview state are not intended for production use and so are not covered by security bulletins until they exit preview state.)
Next step

What the vendor recommends

We have pushed updates to both the Early Access and Normal update channels of XenServer 8.4. We recommend that customers update to the latest version from their chosen channel following the instructions at https://docs.xenserver.com/en-us/xenserver/8/update

Review the complete instructions on the vendor's site
Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

    • The vendor changed its remediation guidance.
Timeline

When this advisory changed

  1. Published by Citrix

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Confirmed at the source

    Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-23558View CVSS, KEV, EPSS, and threat contextCVE-2026-23556View CVSS, KEV, EPSS, and threat contextCVE-2026-23559View CVSS, KEV, EPSS, and threat contextCVE-2026-23560View CVSS, KEV, EPSS, and threat contextCVE-2026-23561View CVSS, KEV, EPSS, and threat contextCVE-2025-54505View CVSS, KEV, EPSS, and threat context
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