CVE-2018-12891
Published: 2 July 2018
An issue was discovered in Xen through 4.10.x. Certain PV MMU operations may take a long time to process. For that reason Xen explicitly checks for the need to preempt the current vCPU at certain points. A few rarely taken code paths did bypass such checks. By suitably enforcing the conditions through its own page table contents, a malicious guest may cause such bypasses to be used for an unbounded number of iterations. A malicious or buggy PV guest may cause a Denial of Service (DoS) affecting the entire host. Specifically, it may prevent use of a physical CPU for an indeterminate period of time. All Xen versions from 3.4 onwards are vulnerable. Xen versions 3.3 and earlier are vulnerable to an even wider class of attacks, due to them lacking preemption checks altogether in the affected code paths. Only x86 systems are affected. ARM systems are not affected. Only multi-vCPU x86 PV guests can leverage the vulnerability. x86 HVM or PVH guests as well as x86 single-vCPU PV ones cannot leverage the vulnerability.
Notes
| Author | Note |
|---|---|
| mdeslaur | hypervisor packages are in universe. For issues in the hypervisor, add appropriate tags to each section, ex: Tags_xen: universe-binary |
Priority
Status
| Package | Release | Status |
|---|---|---|
|
xen Launchpad, Ubuntu, Debian |
artful |
Ignored
(end of life)
|
| bionic |
Needed
|
|
| cosmic |
Ignored
(end of life)
|
|
| disco |
Ignored
(end of life)
|
|
| eoan |
Ignored
(end of life)
|
|
| focal |
Not vulnerable
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| groovy |
Ignored
(end of life)
|
|
| hirsute |
Ignored
(end of life)
|
|
| impish |
Ignored
(end of life)
|
|
| jammy |
Not vulnerable
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| kinetic |
Not vulnerable
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| lunar |
Not vulnerable
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| mantic |
Not vulnerable
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| noble |
Not vulnerable
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| trusty |
Does not exist
(trusty was needs-triage)
|
|
| upstream |
Released
(4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9)
|
|
| xenial |
Needed
|
|
| Binaries built from this source package are in Universe and so are supported by the community. | ||
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 6.5 |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Changed |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |