Bulletin ID: HCSEC-2026-46
Affected Products / Versions: Consul and Consul Enterprise 1.17.0 up to 2.0.4; fixed in Consul 2.1.0 and Consul Enterprise 2.1.0 and 1.21.19
Publication Date: October 26, 2026
Summary
HashiCorp Consul and Consul Enterprise 1.17.0 up to 2.0.4 are vulnerable to an authorization bypass in the agent’s service mesh leaf certificate API that may allow an attacker without a valid ACL token to retrieve a cached service leaf certificate and its private key. This vulnerability (CVE-2026-105765) is fixed in Consul Community Edition 2.1.0 and Consul Enterprise 2.1.0 and 1.21.19.
Background
Consul service mesh issues each service a leaf certificate, which proxies and Connect-native applications use to establish mutual TLS (mTLS) connections and to identify the service to other services in the mesh. Consul agents can return a service’s leaf certificate and private key through the agent HTTP API, and cache issued certificates to reduce load on Consul servers.
Details
Consul agents enforced the service:write requirement only when a new leaf certificate had to be issued. When a valid certificate for the requested service was already cached on the agent, the agent returned it without verifying the caller’s ACL token. An attacker with network access to the agent’s HTTP API could retrieve that certificate and its private key without a valid ACL token, and could potentially use them to impersonate the service in the mesh and reach services that intentions permit for that identity. Exposure is limited to certificates already cached on the reachable agent, which typically includes services whose sidecar proxies are managed by that agent; Consul servers that manage proxies for Consul Dataplane deployments may cache certificates for many services. This issue only affects deployments with ACLs enabled. By default, the agent HTTP API listens only on the loopback interface, which limits exposure to processes on the same host.
Remediation
Customers should evaluate the risk associated with this issue and consider upgrading to Consul Community Edition 2.1.0 or Consul Enterprise 2.1.0 or 1.21.19. Customers that cannot upgrade immediately may restrict network access to the agent HTTP API, or block the agent leaf certificate endpoint with http_config.block_endpoints if no Connect-native applications or consul-template configurations on that agent depend on it.
Acknowledgement
This issue was reported to HashiCorp by Tomas Castillo (muertostech · GitHub).
We deeply appreciate any effort to coordinate disclosure of security vulnerabilities. For information about security at HashiCorp and the reporting of security vulnerabilities, please see https://hashicorp.com/security.