UBUNTU-CVE-2021-26933

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Source
https://ubuntu.com/security/CVE-2021-26933
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-26933.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2021-26933
Upstream
Published
2021-02-17T02:15:00Z
Modified
2025-09-08T16:47:01Z
Severity
  • 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

An issue was discovered in Xen 4.9 through 4.14.x. On Arm, a guest is allowed to control whether memory accesses are bypassing the cache. This means that Xen needs to ensure that all writes (such as the ones during scrubbing) have reached the memory before handing over the page to a guest. Unfortunately, the operation to clean the cache is happening before checking if the page was scrubbed. Therefore there is no guarantee when all the writes will reach the memory.

References

Affected packages

Ubuntu:Pro:16.04:LTS / xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen@4.6.5-0ubuntu1.4?arch=source&distro=esm-infra/xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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": "libxen-dev",
            "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"
        }
    ]
}

Ubuntu:Pro:18.04:LTS / xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen@4.9.2-0ubuntu1?arch=source&distro=esm-infra/bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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": "libxen-dev",
            "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"
        }
    ]
}

Ubuntu:Pro:20.04:LTS / xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen@4.11.3+24-g14b62ab3e5-1ubuntu2.3?arch=source&distro=esm-apps/focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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": "libxen-dev",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        },
        {
            "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"
        }
    ]
}

Ubuntu:22.04:LTS / xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen@4.16.0-1~ubuntu2.1?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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": "libxen-dev",
            "binary_version": "4.16.0-1~ubuntu2.1"
        },
        {
            "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"
        }
    ]
}

Ubuntu:24.04:LTS / xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen@4.17.3+10-g091466ba55-1.1ubuntu3?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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": "libxen-dev",
            "binary_version": "4.17.3+10-g091466ba55-1.1ubuntu3"
        },
        {
            "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"
        }
    ]
}

Ubuntu:25.04 / xen

Package

Name
xen
Purl
pkg:deb/ubuntu/xen@4.20.0-1ubuntu1?arch=source&distro=plucky

Affected ranges

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

Affected versions

4.*

4.17.3+10-g091466ba55-1.1ubuntu3
4.19.1-1ubuntu3
4.20.0-1ubuntu1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libxen-dev",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxencall1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxendevicemodel1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxenevtchn1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxenforeignmemory1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxengnttab1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxenhypfs1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxenmisc4.20",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxenstore4",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxentoolcore1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "libxentoollog1",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.20-amd64",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-4.20-arm64",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-utils-4.20",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xen-utils-common",
            "binary_version": "4.20.0-1ubuntu1"
        },
        {
            "binary_name": "xenstore-utils",
            "binary_version": "4.20.0-1ubuntu1"
        }
    ]
}