CVE-2023-5043 in ingress-nginx
Summary
by MITRE • 10/25/2023
Ingress nginx annotation injection causes arbitrary command execution.
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Analysis
by VulDB Data Team • 02/14/2025
The vulnerability identified as CVE-2023-5043 represents a critical security flaw in the NGINX ingress controller that enables remote attackers to inject arbitrary commands through malicious annotations. This issue stems from improper input validation and sanitization within the ingress controller's handling of Kubernetes annotations, specifically when processing user-provided values that are subsequently used in command execution contexts. The flaw exists in the way the ingress controller interprets and processes annotation values that are meant to configure NGINX behavior, creating a path for command injection attacks that can be exploited by unauthorized parties.
The technical implementation of this vulnerability occurs when Kubernetes administrators or users define annotations on ingress resources that contain specially crafted payloads. These annotations are typically used to configure NGINX-specific behaviors such as SSL settings, rate limiting, or custom headers. When the ingress controller processes these annotations, it fails to properly sanitize the input values before incorporating them into system commands or configuration files. This lack of proper input validation creates an environment where attacker-controlled data can be executed as shell commands, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it leverages legitimate configuration mechanisms within Kubernetes to achieve malicious outcomes.
The operational impact of CVE-2023-5043 extends far beyond simple privilege escalation, as it can enable attackers to execute arbitrary code on the ingress controller pod with the privileges of the running process. This access can be leveraged to establish persistent backdoors, exfiltrate sensitive data, or pivot to other systems within the cluster. The attack surface is broad as any user with permissions to create or modify ingress resources can potentially exploit this vulnerability, making it particularly dangerous in multi-tenant environments. Organizations running NGINX ingress controllers without proper mitigation measures face significant risk of unauthorized access and potential data breaches, especially when ingress controllers are exposed to untrusted networks or users with insufficient RBAC controls.
Mitigation strategies for CVE-2023-5043 should focus on both immediate defensive measures and long-term architectural improvements. Organizations should apply the latest patches and updates provided by the NGINX ingress controller maintainers to address the root cause of the vulnerability. Additionally, implementing strict RBAC policies that limit who can create or modify ingress resources is essential to prevent unauthorized exploitation. Input validation and sanitization should be enforced at multiple layers, including the ingress controller configuration and application-level controls. The use of network policies to restrict access to ingress controller components and monitoring systems to detect anomalous command execution patterns can provide additional defense in depth. Organizations should also consider implementing runtime protection mechanisms such as container image hardening and privilege reduction for ingress controller processes to limit potential damage from successful exploitation attempts. This vulnerability aligns with CWE-74 and CWE-88 categories related to injection flaws and command injection respectively, and maps to ATT&CK techniques involving privilege escalation and command execution within containerized environments.