CVE-2022-40716 in Consul
Summary
by MITRE • 09/23/2022
HashiCorp Consul and Consul Enterprise up to 1.11.8, 1.12.4, and 1.13.1 do not check for multiple SAN URI values in a CSR on the internal RPC endpoint, enabling leverage of privileged access to bypass service mesh intentions. Fixed in 1.11.9, 1.12.5, and 1.13.2."
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/28/2025
HashiCorp Consul and Consul Enterprise versions prior to 1.11.9, 1.12.5, and 1.13.2 contain a critical security vulnerability in their internal RPC endpoint implementation that fails to properly validate Subject Alternative Name (SAN) URI values within Certificate Signing Requests. This flaw exists within the certificate validation process where the system accepts CSRs containing multiple SAN URI values without adequate verification, creating a significant bypass opportunity for unauthorized privileged access. The vulnerability specifically impacts the service mesh intentions functionality which governs traffic control and security policies within the Consul mesh architecture, allowing attackers to potentially circumvent intended access controls and gain elevated privileges within the service mesh environment. The technical implementation flaw resides in the certificate validation logic that should enforce strict validation of CSR contents but instead permits malformed or improperly structured certificate requests to proceed. This weakness directly relates to CWE-295 which addresses improper certificate validation and can be categorized under ATT&CK technique T1552.001 for credentials from password storage. The operational impact extends beyond simple privilege escalation as it compromises the fundamental security model of Consul's service mesh by enabling attackers to manipulate certificate-based authentication mechanisms. When exploited, the vulnerability allows malicious actors to bypass service mesh intentions that are designed to control which services can communicate with each other, potentially leading to unauthorized data access, service disruption, or lateral movement within the mesh. The attack vector leverages the internal RPC endpoint where certificate validation occurs, meaning that exploitation could occur through legitimate internal communication channels or by compromising an existing privileged position within the Consul infrastructure. Organizations utilizing Consul service mesh are particularly vulnerable since the flaw affects core authentication and authorization mechanisms that protect service-to-service communications. The fix implemented in versions 1.11.9, 1.12.5, and 1.13.2 addresses this by strengthening the CSR validation logic to properly enforce single SAN URI value constraints and implement comprehensive certificate content verification. Security teams should prioritize immediate patching of affected Consul instances and conduct thorough audits of service mesh intentions and certificate management practices. Additional mitigations include monitoring internal RPC endpoint communications for anomalous certificate request patterns and implementing network segmentation to limit access to critical internal endpoints. The vulnerability demonstrates the importance of robust certificate validation in distributed systems and highlights how seemingly minor implementation gaps can create significant security risks in complex service mesh architectures. This flaw underscores the necessity of comprehensive input validation and proper certificate handling procedures in enterprise security infrastructure, particularly in environments where service mesh technologies are deployed for traffic control and security policy enforcement. Organizations should also review their certificate management workflows and ensure that proper validation controls are in place to prevent similar issues in other components of their infrastructure that handle certificate-based authentication.