CVE-2020-29567 : Vulnerability Insights and Analysis

An issue was discovered in Xen 4.14.x where moving IRQs between CPUs can lead to a Denial of Service (DoS) due to a continuous stream of self-interrupts, rendering the CPU unusable.

Understanding CVE-2020-29567

This CVE involves a vulnerability in Xen 4.14.x that affects x86 systems when handling IRQs and can result in a DoS attack.

What is CVE-2020-29567?

The vulnerability in Xen 4.14.x allows a domain with a passed-through PCI device to cause a lockup of a physical CPU, leading to a DoS attack on the entire host. Only x86 systems are vulnerable, while Arm systems are not affected.

The Impact of CVE-2020-29567

The vulnerability can render the CPU effectively unusable, causing a Denial of Service to the host when exploited by guests with physical PCI devices passed through to them.

Technical Details of CVE-2020-29567

This section provides more in-depth technical information about the CVE.

Vulnerability Description

IRQ vectors are dynamically allocated and de-allocated on relevant CPUs in Xen 4.14.x
De-allocation must meet specific constraints; otherwise, a continuous stream of self-interrupts can occur

Affected Systems and Versions

Only x86 systems running Xen 4.14.x are vulnerable
Arm systems are not impacted by this vulnerability

Exploitation Mechanism

Guests with physical PCI devices passed through to them can exploit the vulnerability

Mitigation and Prevention

Protecting systems from CVE-2020-29567 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply patches provided by Xen to address the vulnerability
Monitor system behavior for any signs of unusual CPU activity

Long-Term Security Practices

Regularly update Xen and other software components to prevent vulnerabilities
Implement network segmentation to limit the impact of potential attacks

Patching and Updates

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