CVE-2021-3750 : What You Need to Know

A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU. This vulnerability affects QEMU versions before 7.0.0, allowing a malicious guest to crash the QEMU process on the host, resulting in a denial of service condition, or potentially execute arbitrary code within the context of the QEMU process on the host. The vulnerability is classified under CWE-416.

Understanding CVE-2021-3750

This section provides insights into the impact, technical details, and mitigation strategies related to CVE-2021-3750.

What is CVE-2021-3750?

CVE-2021-3750 is a DMA reentrancy issue in the USB EHCI controller emulation of QEMU, enabling a malicious guest to trigger undesirable actions on the host, leading to a use-after-free issue.

The Impact of CVE-2021-3750

The vulnerability allows a malicious actor to crash the QEMU process on the host system, potentially resulting in denial of service conditions or arbitrary code execution within the context of the QEMU process.

Technical Details of CVE-2021-3750

This section elaborates on the vulnerability description, affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

A DMA reentrancy issue in the USB EHCI controller emulation of QEMU allows crafted content to be written to the controller's registers, triggering undesirable actions during USB packet transfer, potentially leading to a use-after-free issue.

Affected Systems and Versions

QEMU versions before 7.0.0 are impacted by this vulnerability, specifically affecting the USB EHCI controller emulation.

Exploitation Mechanism

Malicious guests can exploit this flaw by writing crafted content to trigger actions on the host system, ultimately leading to a denial of service condition or arbitrary code execution.

Mitigation and Prevention

This section outlines immediate steps to take, long-term security practices, and the importance of patching and updates.

Immediate Steps to Take

Users are advised to update QEMU to version 7.0.0 or later to mitigate the vulnerability and prevent potential exploitation.

Long-Term Security Practices

Implementing secure coding practices and regular security assessments can help in identifying and addressing similar vulnerabilities in virtualization software.

Patching and Updates

Regularly monitoring for security advisories and promptly applying patches can enhance the security posture of systems and prevent exploitation of known vulnerabilities.