CVE-2021-38199 : Exploit Details and Defense Strategies

This article provides detailed information about CVE-2021-38199, a vulnerability found in the Linux kernel before version 5.13.4 that could lead to a denial of service attack. Learn about the impact, technical details, and mitigation strategies below.

Understanding CVE-2021-38199

CVE-2021-38199 refers to a vulnerability in fs/nfs/nfs4client.c in the Linux kernel before version 5.13.4. The flaw arises from incorrect connection-setup ordering, enabling operators of remote NFSv4 servers to trigger a denial of service by making servers unreachable during trunking detection.

What is CVE-2021-38199?

The vulnerability in fs/nfs/nfs4client.c in Linux kernel versions prior to 5.13.4 enables malicious operators of remote NFSv4 servers to orchestrate denial of service attacks by disrupting connection-setup ordering.

The Impact of CVE-2021-38199

Operators of remote NFSv4 servers can exploit this vulnerability to cause a denial of service, resulting in the hanging of mounts and disrupting normal system operation.

Technical Details of CVE-2021-38199

The following technical aspects outline the CVE-2021-38199 vulnerability:

Vulnerability Description

The flaw in fs/nfs/nfs4client.c in the Linux kernel before 5.13.4 allows remote NFSv4 server operators to induce denial of service by manipulating server reachability during trunking detection.

Affected Systems and Versions

All Linux kernel versions before 5.13.4 are impacted by CVE-2021-38199 due to incorrect connection-setup ordering in fs/nfs/nfs4client.c.

Exploitation Mechanism

The vulnerability can be exploited remotely by operators of NFSv4 servers who can disrupt connection-setup ordering to trigger a denial of service attack.

Mitigation and Prevention

Understanding and implementing the following measures can help mitigate the risks associated with CVE-2021-38199:

Immediate Steps to Take

System administrators and users are advised to update their Linux kernel to version 5.13.4 or later to address the vulnerability and prevent potential denial of service attacks.

Long-Term Security Practices

Regularly monitoring and applying security updates to the Linux kernel can help prevent future vulnerabilities and enhance overall system security.

Patching and Updates

Staying informed about security advisories and promptly applying patches released by Linux distributors can significantly reduce the risk of exploitation.