CVE-2021-3929 : Exploit Details and Defense Strategies

A DMA reentrancy issue in the NVM Express Controller (NVME) emulation in QEMU exposes a vulnerability. This vulnerability, similar to CVE-2021-3750, can allow a malicious guest to crash the QEMU process or potentially execute arbitrary code on the host.

Understanding CVE-2021-3929

This section delves into the details of the CVE-2021-3929 vulnerability in QEMU.

What is CVE-2021-3929?

CVE-2021-3929 is a DMA reentrancy vulnerability found in the NVM Express Controller (NVME) emulation in QEMU. Exploiting this flaw could lead to a denial of service condition or the execution of arbitrary code on the host.

The Impact of CVE-2021-3929

The impact of CVE-2021-3929 includes the potential to crash the QEMU process on the host, resulting in a denial of service scenario or unauthorized code execution.

Technical Details of CVE-2021-3929

This section provides technical insights into the CVE-2021-3929 vulnerability.

Vulnerability Description

The vulnerability stems from a DMA reentrancy issue in the NVME emulation within QEMU, which may lead to a use-after-free problem. An attacker could exploit this to crash the QEMU process or execute malicious code.

Affected Systems and Versions

QEMU versions that are affected include those up to qemu-kvm 7.0.0-rc0.

Exploitation Mechanism

The vulnerability occurs when the reentrancy write triggers the reset function nvme_ctrl_reset(), leading to the freeing of data structs and subsequent use-after-free issues.

Mitigation and Prevention

Learn how to protect your systems from the CVE-2021-3929 vulnerability.

Immediate Steps to Take

Immediately update QEMU to version 7.0.0-rc0 or later to mitigate the risk associated with CVE-2021-3929.

Long-Term Security Practices

Incorporate regular software updates and security patches into your system maintenance practices to prevent future vulnerabilities.

Patching and Updates

Stay informed about security advisories and apply relevant patches promptly to keep your systems secure.