CVE-2020-7219 in Consul
Summary
by MITRE
HashiCorp Consul and Consul Enterprise up to 1.6.2 HTTP/RPC services allowed unbounded resource usage, and were susceptible to unauthenticated denial of service. Fixed in 1.6.3.
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Analysis
by VulDB Data Team • 08/31/2025
HashiCorp Consul and Consul Enterprise versions prior to 1.6.3 contained a critical vulnerability in their HTTP/RPC services that enabled unbounded resource consumption and created significant denial of service attack vectors. This vulnerability allowed attackers to exploit the service endpoints without authentication, leading to potential system exhaustion and service disruption. The flaw specifically affected the HTTP and RPC interfaces that handle various administrative and operational functions within the Consul service mesh ecosystem.
The technical implementation of this vulnerability stemmed from insufficient input validation and resource management within the HTTP/RPC service handlers. Attackers could send malicious requests that would cause the system to consume excessive memory and CPU resources without proper bounds or rate limiting mechanisms. This lack of resource control meant that a single malicious request could potentially cause the entire Consul service to become unresponsive or crash entirely. The vulnerability was particularly dangerous because it required no authentication credentials, making it accessible to any external party with network access to the affected services.
The operational impact of this vulnerability extended beyond simple service disruption to potentially compromise entire service mesh infrastructures. Organizations relying on Consul for service discovery, health checking, and configuration management faced significant risks when exposed to unauthenticated denial of service attacks. The vulnerability could be exploited to cause cascading failures throughout distributed systems that depend on Consul for critical operational functions. Network administrators and security teams would experience service interruptions that could affect hundreds or thousands of microservices depending on the scale of Consul deployment.
Security professionals should prioritize immediate remediation by upgrading to Consul version 1.6.3 or later, which includes proper resource limits and authentication requirements for HTTP/RPC services. Additional mitigations include implementing network-level access controls to restrict access to Consul HTTP/RPC endpoints, deploying intrusion detection systems to monitor for suspicious traffic patterns, and establishing proper monitoring for unusual resource consumption. The vulnerability aligns with CWE-400, which addresses "Uncontrolled Resource Consumption," and represents a significant concern in the ATT&CK framework under the "Resource Exhaustion" technique category. Organizations should also consider implementing rate limiting mechanisms and proper access controls to prevent similar vulnerabilities in other services within their infrastructure.