CVE-2018-16871 Explained : Impact and Mitigation

A vulnerability has been identified in the Linux kernel's NFS implementation, affecting all versions 3.x and versions 4.x up to 4.20. If an adversary manages to mount an exported NFS filesystem, they can exploit this flaw by utilizing an invalid NFS sequence, leading to a null pointer dereference. This can result in a machine panic and restricted access to the NFS server, with pending disk writes to the NFS server being forfeited.

Understanding CVE-2018-16871

This CVE affects the Linux kernel's NFS implementation, impacting Red Hat systems.

What is CVE-2018-16871?

CVE-2018-16871 is a vulnerability in the Linux kernel's NFS implementation that allows attackers to trigger a null pointer dereference by using an invalid NFS sequence, potentially leading to a machine panic and restricted access to the NFS server.

The Impact of CVE-2018-16871

The vulnerability has a CVSS base score of 7.5, indicating a high severity issue. The impact includes a machine panic, restricted access to the NFS server, and forfeiture of pending disk writes.

Technical Details of CVE-2018-16871

This section provides more technical insights into the vulnerability.

Vulnerability Description

The vulnerability in the Linux kernel's NFS implementation allows for a null pointer dereference when an adversary exploits an invalid NFS sequence.

Affected Systems and Versions

Affected Product: Red Hat
Affected Versions: All 3.x, all 4.x up to 4.20

Exploitation Mechanism

The flaw can be exploited by mounting an exported NFS filesystem and utilizing an invalid NFS sequence to trigger the null pointer dereference.

Mitigation and Prevention

Protecting systems from CVE-2018-16871 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply relevant patches provided by Red Hat to address the vulnerability.
Monitor and restrict access to NFS servers to prevent unauthorized mounting.

Long-Term Security Practices

Regularly update and patch systems to mitigate known vulnerabilities.
Implement network segmentation to limit the impact of potential attacks.

Patching and Updates

Refer to Red Hat advisories RHSA-2019:2696, RHSA-2019:2730, RHSA-2020:0740 for patching guidance.