CVE-2020-11743 : Security Advisory and Response

An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service due to a bad error path in GNTTABOP_map_grant.

Understanding CVE-2020-11743

What is CVE-2020-11743?

CVE-2020-11743 is a vulnerability in Xen through version 4.13.x that enables guest OS users to trigger a denial of service by exploiting a flaw in GNTTABOP_map_grant.

The Impact of CVE-2020-11743

The vulnerability allows a buggy or malicious guest to crash a Linux-based dom0 or backend domain by manipulating the grant table in a specific way.

Technical Details of CVE-2020-11743

Vulnerability Description

The issue arises from a bad error path in GNTTABOP_map_grant in Xen through version 4.13.x.
Misplaced brackets cause an error path to return 1 instead of a negative value, leading to incorrect initialization.

Affected Systems and Versions

Xen through version 4.13.x is affected by this vulnerability.

Exploitation Mechanism

A guest OS user can construct the grant table to trigger the incorrect error path when a backend domain attempts to map a grant, resulting in a denial of service.

Mitigation and Prevention

Immediate Steps to Take

Apply patches provided by Xen to address the vulnerability.
Monitor Xen security advisories for updates and apply them promptly.

Long-Term Security Practices

Regularly update Xen and other software components to mitigate potential security risks.

Patching and Updates

Stay informed about security updates and apply them as soon as they are available.