CVE-2023-27595 : What You Need to Know

This CVE affects Cilium containers where eBPF filters may be temporarily removed during agent restart, potentially leading to disruptions in network connectivity and security features.

Understanding CVE-2023-27595

This vulnerability in Cilium version 1.13.0 involves a window during restart where Cilium eBPF programs are not attached to the host, impacting network connectivity and security features.

What is CVE-2023-27595?

Cilium is a networking, observability, and security solution utilizing an eBPF-based dataplane. This CVE specifically affects Cilium version 1.13.0, where a short period of non-attachment of eBPF programs during startup can cause disruptions in network policies, load balancing, and overall feature implementation.

The Impact of CVE-2023-27595

This vulnerability can lead to disruptions in newly established connections, potential network policy bypass, and compromises in security enforcement during the affected window. Any Cilium-managed endpoints on the node, such as Kubernetes Pods, and the host network namespace are at risk.

Technical Details of CVE-2023-27595

In Cilium version 1.13.0, a specific timing issue during startup causes the temporary removal of eBPF programs, resulting in potential service disruptions and security vulnerabilities.

Vulnerability Description

The vulnerability arises from a period during Cilium startup when eBPF programs are not attached to the host, impacting the implementation of Cilium's featureset and leading to possible disruptions in network functionality and security enforcement.

Affected Systems and Versions

Vendor: Cilium
Product: Cilium
Affected Version: 1.13.0
Status: Affected
Versions: Cilium releases 1.12.x, 1.11.x, and earlier are not impacted.

Exploitation Mechanism

The vulnerability exposes Cilium-managed endpoints and the host network namespace to potential disruptions and security bypasses during the startup window where eBPF programs are temporarily detached.

Mitigation and Prevention

To address CVE-2023-27595 and mitigate its impact, immediate actions and long-term security measures need to be implemented.

Immediate Steps to Take

Upgrade to Cilium version 1.13.1 or later to fix the vulnerability.
Implement additional network security measures to compensate for the potential window of vulnerability during agent restarts.

Long-Term Security Practices

Maintain regular updates and patches for Cilium and related components to stay protected against emerging vulnerabilities.
Continuously monitor network activity and security configurations to detect any anomalies or potential exploits.

Patching and Updates

Ensure timely updates to Cilium version 1.13.1 or later to mitigate the vulnerability and prevent disruptions in network functionality and security enforcement.