Kestra: Unauthenticated management/actuator endpoints exposed on port 8081 (/env, /loggers) bypass API basic-auth

Summary

Kestra's Micronaut management endpoints are served on port 8081 with no authentication, even when the main API (port 8080) has basic-auth enabled. Anyone who can reach :8081 can read GET /env (full resolved environment/configuration) and mutate runtime state via POST /loggers/{name} (change log levels), among the other management endpoints. Enabling basic-auth creates a false sense of protection because the auth filter only covers /api/v1/** on 8080 and never applies to the 8081 management port. The shipped repository contains no statement that 8081 is management-only / must-not-be-exposed, and the vendor's reference docker-compose.yml publishes it with no warning.

Affected

• Product: Kestra (kestra-io/kestra), an open-source orchestration/data-pipeline platform (Java / Micronaut).
• Version: v1.3.29 (confirmed); the management-port exposure is an insecure default of the shipped configuration.
• No fix at time of report.

Technical detail

Kestra runs the Micronaut management/actuator endpoints on a separate HTTP port 8081. The authentication filter (basic-auth, when configured) is scoped to the main API on port 8080 (/api/v1/**) and does not apply to 8081. As a result:

• GET http://<host>:8081/env returns the full resolved environment/configuration (property sources), unauthenticated.
• POST http://<host>:8081/loggers/{name} changes a logger's level at runtime, unauthenticated (a state-changing operation).
• The other Micronaut management endpoints on 8081 are similarly reachable. The shipped application.yml comments, SECURITY.md, and the vendor's reference docker-compose.yml do not warn that 8081 must be kept internal, and the reference compose publishes 8081, so a deployment that enables basic-auth on the API still exposes the management port with no auth.

Impact

An unauthenticated network client that can reach port 8081 can read the full application configuration/environment (/env) and change runtime logging (/loggers), and reach the other management endpoints — an authentication-bypass on the management surface. (Sensitive credential values in /env are masked, so this is scored without a full-secret-read confidentiality impact.)

Proof of concept

Reproduced live on Kestra v1.3.29 with basic-auth enabled on the main API. Unauthenticated GET http://<host>:8081/env returned 200 with the resolved configuration/property sources, and POST http://<host>:8081/loggers/{name} returned 200 and changed the logger level — both with no credentials. The equivalent main-API request on 8080 returned 401 (control), confirming the auth filter covers only the API port and not the 8081 management port. (Credential values in /env were masked.)

Full request/response captures available on request.

Remediation

Apply authentication to the management port (bind the Micronaut management endpoints behind the same auth as the API, or require a separate management credential), and by default bind port 8081 to loopback only. At minimum, document prominently (SECURITY.md, application.yml, the reference docker-compose) that port 8081 must never be exposed to untrusted networks, and do not publish 8081 in the reference compose.

Credit

Reported by Santosh Kumar Puppala (GitHub: https://github.com/Santoshkumarpuppala).