CVE-2020-8554 in Communications Cloud Native Core Policy
Summary
by MITRE • 01/22/2021
Kubernetes API server in all versions allow an attacker who is able to create a ClusterIP service and set the spec.externalIPs field, to intercept traffic to that IP address. Additionally, an attacker who is able to patch the status (which is considered a privileged operation and should not typically be granted to users) of a LoadBalancer service can set the status.loadBalancer.ingress.ip to similar effect.
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Analysis
by VulDB Data Team • 06/02/2026
The vulnerability described in CVE-2020-8554 represents a significant security flaw within the Kubernetes API server that enables unauthorized traffic interception through improper service configuration handling. This vulnerability affects all versions of Kubernetes and stems from insufficient validation of external IP address specifications within service definitions, creating a pathway for malicious actors to manipulate network traffic flow. The flaw specifically manifests when attackers can create ClusterIP services with the spec.externalIPs field populated or when they can patch LoadBalancer service status fields, both of which should normally require elevated privileges to modify. The technical implementation of this vulnerability exploits the lack of proper access controls and validation mechanisms within the Kubernetes control plane, allowing attackers to effectively hijack network traffic destined for specific IP addresses.
The operational impact of this vulnerability extends beyond simple traffic interception, potentially enabling man-in-the-middle attacks, data exfiltration, and service disruption across containerized environments. When an attacker successfully sets externalIPs on a ClusterIP service, they can redirect traffic intended for legitimate external services to their own endpoints, creating a vector for credential theft, session hijacking, and other network-based attacks. The LoadBalancer patching component adds additional risk as it allows attackers to manipulate ingress information, potentially causing legitimate services to route traffic through compromised endpoints. This vulnerability directly violates the principle of least privilege and demonstrates weaknesses in Kubernetes' RBAC (Role-Based Access Control) implementation, where privilege escalation can occur through seemingly innocuous service configuration modifications. The attack vector is particularly concerning in multi-tenant environments where different users or teams share the same cluster infrastructure.
Mitigation strategies for CVE-2020-8554 require immediate implementation of enhanced access controls and network segmentation measures. Organizations should strictly enforce RBAC policies to prevent non-privileged users from creating or modifying service configurations, particularly those involving external IP addresses. The Kubernetes API server should be configured to validate all external IP address specifications against known legitimate ranges and implement strict network policy enforcement. Additionally, monitoring solutions should be deployed to detect anomalous service creation or modification patterns, particularly around externalIPs and LoadBalancer ingress fields. The vulnerability aligns with CWE-284 (Improper Access Control) and can be mapped to ATT&CK techniques including T1071.004 (Application Layer Protocol: DNS) and T1566 (Phishing). Organizations should also consider implementing network-level protections such as IP address whitelisting, traffic inspection, and regular security auditing of service configurations to prevent exploitation of this vulnerability in production environments.