CVE-2020-8663 in Envoy
Summary
by MITRE
Envoy version 1.14.2, 1.13.2, 1.12.4 or earlier may exhaust file descriptors and/or memory when accepting too many connections.
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Analysis
by VulDB Data Team • 10/28/2020
The vulnerability identified as CVE-2020-8663 affects Envoy proxy versions 1.14.2, 1.13.2, and 1.12.4 or earlier, presenting a significant security risk through resource exhaustion attacks. This flaw manifests when the proxy encounters an excessive number of concurrent connections, leading to potential denial of service conditions that can compromise system availability and performance. The vulnerability operates at the connection management layer of the Envoy proxy, which serves as a critical component in modern service mesh architectures and API gateways. Organizations relying on Envoy for traffic management face substantial operational risks when this vulnerability remains unaddressed, particularly in high-traffic environments where connection handling becomes a performance bottleneck.
The technical root cause of this vulnerability stems from inadequate resource management within the connection handling mechanisms of the Envoy proxy. When the proxy receives a large volume of connections beyond its configured limits, it fails to properly manage file descriptor allocation and memory consumption patterns. This results in gradual resource exhaustion that can eventually lead to the proxy becoming unresponsive or crashing entirely. The flaw is categorized under CWE-400, which addresses Uncontrolled Resource Consumption, specifically focusing on resource exhaustion attacks that target file descriptors and memory allocation. The vulnerability demonstrates characteristics of a DoS attack vector where an attacker can systematically consume available system resources to prevent legitimate connections from being established.
The operational impact of CVE-2020-8663 extends beyond simple service disruption to encompass broader architectural concerns within microservices environments. In service mesh deployments where Envoy acts as a sidecar proxy, this vulnerability can cascade through the entire system, affecting multiple services simultaneously. The memory exhaustion aspect particularly impacts systems with limited resources, while file descriptor exhaustion affects the maximum number of concurrent connections that can be handled. This vulnerability directly aligns with ATT&CK technique T1499.004, which covers Resource Exhaustion, and demonstrates how attackers can leverage connection management flaws to achieve persistent denial of service conditions. Organizations implementing Envoy in production environments face the risk of operational degradation, increased latency, and potential service outages that can significantly impact user experience and business continuity.
Mitigation strategies for this vulnerability require immediate deployment of patched versions of Envoy, specifically versions 1.14.3, 1.13.3, or 1.12.5 and later. System administrators should implement connection rate limiting and connection pooling configurations to prevent overwhelming the proxy with excessive concurrent connections. Network-level controls such as load balancer configurations and connection tracking rules can help distribute traffic more effectively and prevent resource exhaustion scenarios. Additionally, monitoring systems should be enhanced to detect unusual connection patterns and trigger alerts when resource consumption approaches critical thresholds. The remediation process should include comprehensive testing of patched environments to ensure that the fix does not introduce regressions in functionality while maintaining the proxy's intended performance characteristics. Organizations should also review their connection management policies and implement proper resource allocation strategies to prevent similar vulnerabilities from emerging in other components of their infrastructure.