CVE-2023-6476 Explained : Impact and Mitigation

A flaw was discovered in CRI-O that allows pods to break out of resource confinement on cgroupv2, potentially leading to a denial of service in the node.

Understanding CVE-2023-6476

This section delves into the details of CVE-2023-6476, highlighting its impact, technical aspects, affected systems, and mitigation strategies.

What is CVE-2023-6476?

CVE-2023-6476 is a vulnerability found in CRI-O, an OCI-compatible implementation of Kubernetes Container Runtime Interface, that enables a container to be unconfined through an experimental annotation. This flaw may empower a pod to bypass the Kubernetes scheduler, enabling it to specify and access any amount of memory/CPU.

The Impact of CVE-2023-6476

This vulnerability could result in a pod circumventing resource limitations, potentially leading to a denial of service on the node where it is running. The ability to consume excessive resources may disrupt the normal operation of the node, affecting overall system performance and stability.

Technical Details of CVE-2023-6476

CVE-2023-6476 has been evaluated with a CVSS v3.1 score of 6.5, indicating a moderate severity level. The base severity is classified as medium with high availability impact. The attack complexity is low, and the attack vector is through the network.

Vulnerability Description

The flaw in CRI-O involves an experimental annotation that allows a container to be unconfined, enabling pods to circumvent resource restrictions and potentially cause a denial of service on the node.

Affected Systems and Versions

Red Hat OpenShift Container Platform 4.13 and 4.14 are affected by this vulnerability.
Fedora and Extra Packages for Enterprise Linux are also impacted.

Exploitation Mechanism

By leveraging the experimental annotation in CRI-O, a malicious actor could craft a container that evades resource confinement within the Kubernetes environment, thereby disrupting the node's operational integrity.

Mitigation and Prevention

To safeguard systems from the risks associated with CVE-2023-6476, immediate actions need to be taken alongside long-term security practices.

Immediate Steps to Take

Apply necessary patches and updates provided by Red Hat for the affected products.
Monitor and restrict experimental features that could potentially introduce security vulnerabilities in container runtimes.

Long-Term Security Practices

Regularly update and patch container runtimes to address emerging vulnerabilities.
Implement strict access controls and resource quotas to mitigate the impact of container breakout attempts.
Stay informed about security advisories and best practices for securing containerized environments.

Patching and Updates

Ensure that the CRI-O package on affected systems is updated to the patched versions to mitigate the CVE-2023-6476 vulnerability. Check the respective vendor advisories and package repositories for the latest patches and updates.