Homepage

Out-of-Bounds The advisory has been revoked - it doesn't affect any version of package xen  (opens in a new tab)

Threat Intelligence

EPSS
0.29% (21st percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-UBUNTU1604-XEN-1147554
  • published20 Sept 2022
  • disclosed14 Apr 2020
Report a new vulnerability Found a mistake?

Introduced: 14 Apr 2020

CVE-2020-11739  (opens in a new tab)
CWE-119  (opens in a new tab)

Amendment

The Ubuntu security team deemed this advisory irrelevant for Ubuntu:16.04.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Ubuntu.

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.

References