CVE-2026-53576 PoC — Kestra: Unauthenticated RCE via /configs path-suffix auth-filter bypass

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-53576.yaml

Associated Vulnerability

Title: Kestra: Unauthenticated RCE via /configs path-suffix auth-filter bypass (CVE-2026-53576)
Description:Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, the authentication filter for the REST API (@Filter("/api/v1/**")) treats any request whose path ends in /configs as the public instance-config endpoint and forwards it without a credential check. kestra addresses its resources by URL path segments that the caller chooses (/api/v1/{tenant}/flows/{namespace}, /api/v1/{tenant}/executions/{namespace}/{id}, /api/v1/{tenant}/namespaces/{namespace}/kv/{key}). An anonymous caller picks the literal configs as the final segment, and the request bypasses Basic-Auth entirely. Because the bypass reaches the flow-create and execution-trigger routes, an unauthenticated caller creates a flow containing a Shell or Process task and runs it. The task executes as root inside the kestra container. The official docker-compose.yml mounts /var/run/docker.sock, so root in the container reaches the host Docker daemon. This vulnerability is fixed in 1.0.45 and 1.3.21.

Description

Kestra <= 1.3.20 contains an authentication bypass caused by misclassification of /configs endpoint in REST API filter, letting unauthenticated attackers create and execute root-level tasks, exploit requires unauthenticated access to /configs endpoint.

File Snapshot

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