CVE-2020-8551 in kubelet
Summary
by MITRE
The Kubelet component in versions 1.15.0-1.15.9, 1.16.0-1.16.6, and 1.17.0-1.17.2 has been found to be vulnerable to a denial of service attack via the kubelet API, including the unauthenticated HTTP read-only API typically served on port 10255, and the authenticated HTTPS API typically served on port 10250.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 05/12/2024
The vulnerability identified as CVE-2020-8551 affects the Kubernetes kubelet component across specific version ranges, presenting a significant denial of service risk through the kubelet API interfaces. This flaw exists within the core container orchestration platform that manages node-level operations and serves as the primary interface between the Kubernetes control plane and worker nodes. The affected versions encompass multiple release streams including 1.15.x, 1.16.x, and 1.17.x, indicating a widespread impact across several major Kubernetes releases. The vulnerability specifically targets the kubelet's API endpoints that are accessible through both unauthenticated and authenticated interfaces, creating multiple attack vectors for potential exploitation.
The technical flaw manifests in the kubelet's handling of API requests, where the component fails to properly validate or limit incoming requests to the HTTP read-only API served on port 10255 and the HTTPS authenticated API served on port 10250. This weakness allows attackers to craft malicious requests that can overwhelm the kubelet's processing capabilities, leading to resource exhaustion and ultimately service disruption. The unauthenticated nature of the read-only API on port 10255 makes this vulnerability particularly dangerous as it can be exploited without requiring valid credentials, while the authenticated HTTPS API on port 10250 presents risks even when proper authentication is enforced. The vulnerability is classified under CWE-400, which addresses "Uncontrolled Resource Consumption" or "Resource Exhaustion," highlighting the fundamental issue of inadequate request handling and resource management within the kubelet's API processing logic.
The operational impact of CVE-2020-8551 extends beyond simple service disruption to potentially compromise entire Kubernetes clusters, as the kubelet serves as a critical node component responsible for pod management and container lifecycle operations. When exploited, this vulnerability can cause the affected kubelet instances to become unresponsive, leading to node failures that may result in pod evictions, service interruptions, and cascading failures across the cluster. The attack can be particularly devastating in production environments where multiple nodes are running vulnerable kubelet versions, as the denial of service can propagate across the entire infrastructure. Organizations relying on Kubernetes for mission-critical workloads face significant operational risks, including potential data loss, service degradation, and compliance violations, especially in regulated environments where high availability is mandated.
Mitigation strategies for CVE-2020-8551 should prioritize immediate version upgrades to patched releases of Kubernetes, specifically targeting versions that address this vulnerability within the 1.15.10, 1.16.7, and 1.17.3 release streams. Network-level protections should include firewall rules that restrict access to the kubelet API ports, particularly port 10255 which serves the unauthenticated read-only interface. The principle of least privilege should be enforced by disabling the unauthenticated API where possible and ensuring that only authorized entities can access the authenticated HTTPS endpoints on port 10250. Additionally, implementing rate limiting and request validation mechanisms at the network perimeter can help detect and prevent abuse of the vulnerable API endpoints. Organizations should also consider implementing monitoring solutions that can detect anomalous API request patterns that may indicate exploitation attempts, aligning with ATT&CK framework technique T1499.001 for Network Denial of Service. The remediation process must include comprehensive testing of patched versions in staging environments before deployment to production systems to ensure that the updates do not introduce compatibility issues with existing workloads or configurations.