CVE-2020-11739
Published: 14 April 2020
An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the "critical" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.
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 |
bionic |
Needed
|
eoan |
Ignored
(end of life)
|
|
focal |
Released
(4.11.3+24-g14b62ab3e5-1ubuntu2.3)
|
|
groovy |
Ignored
(end of life)
|
|
hirsute |
Ignored
(end of life)
|
|
impish |
Ignored
(end of life)
|
|
jammy |
Not vulnerable
(4.15.0-1)
|
|
kinetic |
Not vulnerable
(4.15.0-1)
|
|
lunar |
Not vulnerable
(4.15.0-1)
|
|
mantic |
Not vulnerable
(4.15.0-1)
|
|
trusty |
Does not exist
|
|
upstream |
Needs triage
|
|
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 | 7.8 |
Attack vector | Local |
Attack complexity | High |
Privileges required | Low |
User interaction | None |
Scope | Changed |
Confidentiality | High |
Integrity impact | High |
Availability impact | High |
Vector | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H |