CVE-2026-49869

The AuthenticationFilter authentication filter checks the request path using the endsWith('/configs') method, i.e., suffix matching instead of exact path matching. This means any API endpoint whose last segment is 'configs' completely bypasses authentication. An attacker can thus direct a request to an appropriately constructed path, gaining access without credentials. Since Kestra by default provides plugins for executing scripts (plugin-script-shell, plugin-script-python, and others), arbitrary code execution in the worker container context is possible.

An unauthenticated remote attacker can create and execute arbitrary workflows, leading to full RCE with root privileges inside the Kestra worker container, and consequently resulting in environment takeover, data exfiltration, and lateral movement capabilities.

Kestra OSS should be urgently updated to version 1.0.45 or 1.3.21 (depending on the branch in use). Until the patch is deployed, consider restricting network access to the Kestra instance to trusted IP addresses only and disabling script plugins if they are not essential.

Kestra OSS in versions prior to 1.0.45 and prior to 1.3.21

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Kestra OSS contains an OS command injection vulnerability that could allow an unauthenticated remote attacker to create and execute arbitrary workflows without credentials.