CVE-2020-11739 Detail

Current Description

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.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  7.8 HIGH
Vector:  CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H


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Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00006.html
http://www.openwall.com/lists/oss-security/2020/04/14/2 Mailing List  Patch  Third Party Advisory 
http://xenbits.xen.org/xsa/advisory-314.html Patch  Vendor Advisory 
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5M2XRNCHOGGTJQBZQJ7DCV6ZNAKN3LE2/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NVTP4OYHCTRU3ONFJOFJQVNDFB25KLLG/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YMAW7D2MP6RE4BFI5BZWOBBWGY3VSOFN/ Third Party Advisory 
https://security.gentoo.org/glsa/202005-08
https://www.debian.org/security/2020/dsa-4723
https://xenbits.xen.org/xsa/advisory-314.html Patch  Vendor Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer cwe source acceptance level NIST  

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Change History

9 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2020-11739
NVD Published Date:
04/14/2020
NVD Last Modified:
07/13/2020
Source:
MITRE