UBUNTU-CVE-2020-25597

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Source
https://ubuntu.com/security/notices/UBUNTU-CVE-2020-25597
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-25597.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2020-25597
Related
Published
2020-09-23T22:15:00Z
Modified
2020-09-23T22:15:00Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. Note that xl and libxl limit maxeventchannels to 1023 by default, so systems using exclusively xl, libvirt+libxl, or their own toolstack based on libxl, and not explicitly setting maxeventchannels, are not vulnerable.

References

Affected packages

Ubuntu:Pro:16.04:LTS / xen

Package

Name
xen

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 

{
    "ubuntu_priority": "medium"
}

Ubuntu:Pro:18.04:LTS / xen

Package

Name
xen

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 

{
    "ubuntu_priority": "medium"
}

Ubuntu:20.04:LTS / xen

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
4.11.3+24-g14b62ab3e5-1ubuntu2.3

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

Ecosystem specific 

{
    "availability": "No subscription required",
    "ubuntu_priority": "medium",
    "binaries": [
        {
            "xen-doc": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxengnttab1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxendevicemodel1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-4.11-armhf": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-4.9-armhf": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenevtchn1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxentoolcore1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxentoollog1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-common": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-4.9-arm64": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenforeignmemory1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxencall1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-utils-common-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-utils-4.11-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenmisc4.11-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-system-arm64": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xenstore-utils-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenstore3.0": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-4.11-arm64": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxengnttab1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenstore3.0-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-4.9-amd64": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenforeignmemory1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxendevicemodel1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxen-dev": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-system-amd64": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxentoolcore1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxencall1-dbgsym": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xenstore-utils": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenevtchn1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-utils-common": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-system-armhf": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxentoollog1": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-hypervisor-4.11-amd64": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "xen-utils-4.11": "4.11.3+24-g14b62ab3e5-1ubuntu2.3",
            "libxenmisc4.11": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
        }
    ]
}