CVE-2026-49869
Kestra: Unauthenticated Remote Code Execution via Authentication Bypass in `AuthenticationFilter`
Description
Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, AuthenticationFilter in Kestra OSS uses request.getPath().endsWith("/configs") to whitelist the public configuration endpoint from Basic Auth. Because the check is a suffix match rather than an exact path match, any API path whose last segment is configs bypasses authentication entirely. An unauthenticated remote attacker can exploit this to create and execute arbitrary workflows without credentials. Because Kestra ships with script execution plugins (plugin-script-shell, plugin-script-python, etc.) enabled by default, this directly results in unauthenticated Remote Code Execution as root inside the Kestra worker container. This vulnerability is fixed in 1.0.45 and 1.3.21.
In plain language
AI Act nowCVE-2026-49869 is a critical Kestra security flaw where attackers can skip login by using a URL that ends with “/configs”, letting them create and run scripts as the highest-privilege user—so any small business running the vulnerable Kestra versions should act immediately.
Kestra AuthenticationFilter performs an unsafe URL whitelist check using a suffix match (e.g., paths ending in “/configs”) that bypasses authentication, enabling unauthenticated Remote Code Execution to create and execute workflows as root on reachable instances; this is listed in CISA KEV (added 2026-09-02) with a mitigation deadline of 2026-09-05.
What to do now
- Check whether your Kestra is reachable from the internet and whether it runs a Kestra version prior to 1.0.45 (or prior to 1.3.21).
- Confirm whether an attacker could reach the AuthenticationFilter endpoint behavior by verifying your deployed Kestra version and environment exposure (default configs endpoint whitelist is affected when requests target paths ending in “/configs”).
- Upgrade Kestra to a fixed version: install kestra 1.0.45 or later (or upgrade to 1.3.21 or later).
- If you cannot patch immediately, block network access to your Kestra instance from the public internet and ensure only trusted IPs can reach it, then continue with the upgrade.
CVSS Vector Breakdown
AV:NAttack VectorAC:LAttack ComplexityPR:NPrivileges RequiredUI:NUser InteractionS:CScopeC:HConfidentialityI:HIntegrityA:HAvailabilityWeaknesses
Affected Products
Exploitability
Required action: 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.
Attack Graph
Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.
MITRE ATT&CK
4 techniquesReferences
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