CVE-2020-36691 Explained : Impact and Mitigation

An issue was discovered in the Linux kernel before 5.8. lib/nlattr.c allows attackers to cause a denial of service (unbounded recursion) via a nested Netlink policy with a back reference.

Understanding CVE-2020-36691

This CVE identifies a vulnerability in the Linux kernel that could be exploited to trigger a denial of service attack through unbounded recursion.

What is CVE-2020-36691?

The CVE-2020-36691 vulnerability is a flaw in the Linux kernel's lib/nlattr.c file that enables attackers to execute a denial of service attack by utilizing a nested Netlink policy with a back reference.

The Impact of CVE-2020-36691

The exploitation of this vulnerability could lead to a denial of service condition, potentially disrupting the normal operation of affected systems.

Technical Details of CVE-2020-36691

This section delves into the technical aspects of the CVE-2020-36691 vulnerability.

Vulnerability Description

The vulnerability exists in the lib/nlattr.c file of the Linux kernel before version 5.8, allowing attackers to exploit unbounded recursion, leading to a denial of service.

Affected Systems and Versions

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Affected Versions: n/a

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting a nested Netlink policy with a back reference, triggering unbounded recursion and causing a denial of service.

Mitigation and Prevention

To address and prevent the CVE-2020-36691 vulnerability, follow these mitigation strategies:

Immediate Steps to Take

Update to Linux kernel version 5.8 or later to mitigate the vulnerability.
Monitor system logs for any signs of unbounded recursion or denial of service attacks.

Long-Term Security Practices

Regularly update the Linux kernel and other software components to patch known vulnerabilities.
Implement network segmentation and access controls to limit the impact of potential attacks.

Patching and Updates

Apply patches provided by the Linux kernel maintainers promptly to address security vulnerabilities and improve system resilience.