UBUNTU-CVE-2026-23553

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Source
https://ubuntu.com/security/CVE-2026-23553
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-23553
Upstream
Published
2026-01-28T16:16:00Z
Modified
2026-05-20T16:24:43Z
Severity
  • 2.9 (Low) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it was the previous vCPU to run. While safe for Xen's isolation between vCPUs, this prevents the guest kernel correctly isolating between tasks. Consider: 1) vCPU runs on CPU A, running task 1. 2) vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB. 3) On CPU B, guest kernel switches from task 1 to 2, issuing IBPB. 4) vCPU moves back to CPU A. Xen skips IBPB again. Now, task 2 is running on CPU A with task 1's training still in the BTB.

References

Affected packages

Ubuntu:16.04:LTS
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.5.1-0ubuntu1
4.5.1-0ubuntu2
4.6.0-1ubuntu1
4.6.0-1ubuntu2
4.6.0-1ubuntu4
4.6.0-1ubuntu4.1
4.6.0-1ubuntu4.2
4.6.0-1ubuntu4.3
4.6.5-0ubuntu1
4.6.5-0ubuntu1.1
4.6.5-0ubuntu1.2
4.6.5-0ubuntu1.4

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxen-4.6",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "libxenstore3.0",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.4-amd64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.4-arm64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.4-armhf",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.5-amd64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.5-arm64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.5-armhf",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.6-amd64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.6-arm64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-hypervisor-4.6-armhf",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-system-armhf",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-utils-4.6",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.6.5-0ubuntu1.4"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.6.5-0ubuntu1.4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"
Ubuntu:18.04:LTS
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.9.0-0ubuntu3
4.9.0-0ubuntu4
4.9.2-0ubuntu1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxen-4.9",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "libxenstore3.0",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.6-amd64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.6-arm64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.6-armhf",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.7-amd64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.7-arm64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.7-armhf",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.8-amd64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.8-arm64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.8-armhf",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.9-amd64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.9-arm64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.9-armhf",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-system-armhf",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-utils-4.9",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.9.2-0ubuntu1"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.9.2-0ubuntu1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"
Ubuntu:20.04:LTS
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.9.2-0ubuntu2
4.9.2-0ubuntu6
4.9.2-0ubuntu7
4.11.3+24-g14b62ab3e5-1ubuntu1
4.11.3+24-g14b62ab3e5-1ubuntu2
4.11.3+24-g14b62ab3e5-1ubuntu2.2
4.11.3+24-g14b62ab3e5-1ubuntu2.3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxencall1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxendevicemodel1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxenevtchn1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxenforeignmemory1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxengnttab1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxenmisc4.11",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxenstore3.0",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxentoolcore1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "libxentoollog1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-4.11-amd64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-4.11-arm64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-4.11-armhf",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-4.9-amd64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-4.9-arm64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-4.9-armhf",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-system-armhf",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-utils-4.11",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"
Ubuntu:22.04:LTS
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.11.4+24-gddaaccbbab-1ubuntu2
4.16.0-1~ubuntu2
4.16.0-1~ubuntu2.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxencall1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxendevicemodel1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxenevtchn1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxenforeignmemory1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxengnttab1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxenhypfs1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxenmisc4.16",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxenstore4",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxentoolcore1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "libxentoollog1",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-hypervisor-4.16-amd64",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-hypervisor-4.16-arm64",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-hypervisor-4.16-armhf",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-system-armhf",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-utils-4.16",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.16.0-1~ubuntu2.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"
Ubuntu:24.04:LTS
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.17.2-1
4.17.2+55-g0b56bed864-1
4.17.2+76-ge1f9cb16e2-1
4.17.2+76-ge1f9cb16e2-1ubuntu1
4.17.3+10-g091466ba55-1
4.17.3+10-g091466ba55-1.1ubuntu2
4.17.3+10-g091466ba55-1.1ubuntu3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxencall1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxendevicemodel1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxenevtchn1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxenforeignmemory1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxengnttab1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxenhypfs1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxenmisc4.17t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxenstore4t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxentoolcore1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "libxentoollog1t64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-hypervisor-4.17-amd64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-hypervisor-4.17-arm64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-hypervisor-4.17-armhf",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-system-armhf",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-utils-4.17",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"
Ubuntu:25.10
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.20.0-1ubuntu1
4.20.0+68-g35cb38b222-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxencall1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxendevicemodel1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxenevtchn1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxenforeignmemory1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxengnttab1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxenhypfs1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxenmisc4.20",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxenstore4",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxentoolcore1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "libxentoollog1",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-hypervisor-4.20-amd64",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-hypervisor-4.20-arm64",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-utils-4.20",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.20.0+68-g35cb38b222-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"
Ubuntu:26.04:LTS
xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

4.*
4.20.0+68-g35cb38b222-1
4.20.2+7-g1badcf5035-2
4.20.2+7-g1badcf5035-2build2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxencall1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxendevicemodel1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxenevtchn1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxenforeignmemory1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxengnttab1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxenhypfs1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxenmisc4.20",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxenstore4",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxentoolcore1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "libxentoollog1",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-hypervisor-4.20-amd64",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-hypervisor-4.20-arm64",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-utils-4.20",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.20.2+7-g1badcf5035-2build2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23553.json"