CVE-2020-29566 Explained : Impact and Mitigation

An issue was discovered in Xen through 4.14.x where x86 HVM guests could cause a Denial of Service (DoS) to the entire host by triggering a stack overflow. Only x86 systems are affected.

Understanding CVE-2020-29566

This CVE describes a vulnerability in Xen that could be exploited by malicious or buggy stubdomains serving x86 HVM guests, leading to a DoS attack on the host.

What is CVE-2020-29566?

The vulnerability in Xen through version 4.14.x allows x86 HVM guests to crash Xen, resulting in a DoS attack on the entire host.

The Impact of CVE-2020-29566

A malicious or buggy stubdomain serving a HVM guest can cause Xen to crash, leading to a Denial of Service (DoS) attack on the host.
Only x86 systems are affected, while Arm systems remain unaffected.

Technical Details of CVE-2020-29566

This section provides more technical insights into the vulnerability.

Vulnerability Description

X86 HVM guests can exploit a vulnerability in Xen, potentially causing a stack overflow and crashing the system.

Affected Systems and Versions

Only x86 systems running Xen through version 4.14.x are vulnerable to this issue.

Exploitation Mechanism

The vulnerability occurs when x86 HVM guests signal Xen before completing an operation, leading to a repeating de-schedule / re-schedule cycle that could trigger a stack overflow.

Mitigation and Prevention

To address CVE-2020-29566, follow these mitigation strategies:

Immediate Steps to Take

Apply patches provided by Xen to fix the vulnerability.
Monitor system logs for any suspicious activities that could indicate an ongoing attack.

Long-Term Security Practices

Regularly update Xen and other software components to prevent future vulnerabilities.

Patching and Updates

Stay informed about security advisories from Xen and promptly apply patches to secure the system.