CVE-2026-59244 in Airflow
Summary
by MITRE • 08/12/2026
Apache Airflow's secrets masker did not mask `var.json` Variable values whose value is a dict in the Rendered Templates UI — the dict value failed an `isinstance(str)` guard — so a secret stored as a JSON Variable and referenced in a template via `var.json` was displayed in cleartext to any user with access to that task's Rendered Templates view. Users are advised to upgrade to apache-airflow 3.3.1 or later, which masks nested Variable values regardless of type.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability resides within Apache Airflow's secrets management system, specifically affecting the rendered templates user interface where sensitive data exposure occurs due to inadequate input validation. The flaw manifests when variable values stored as JSON objects are accessed through the var.json template function, creating a security gap that bypasses the intended masking mechanisms designed to protect sensitive information. The root cause stems from a type checking mechanism that only validates string instances, failing to account for dictionary or other complex data types that may contain sensitive information.
The technical implementation of this vulnerability operates at the intersection of data serialization and security filtering within Airflow's web interface components. When users access the rendered templates view for tasks, the system attempts to mask sensitive values but employs a restrictive isinstance(str) check that excludes dictionary objects from masking procedures. This design oversight allows attackers with appropriate permissions to extract cleartext secrets directly from task execution interfaces where template rendering occurs, effectively undermining the security controls implemented for variable management.
The operational impact of this vulnerability extends beyond simple information disclosure to create potential attack vectors for privilege escalation and data exfiltration scenarios. Any user with access to the Rendered Templates UI can observe sensitive configuration values, API keys, passwords, or other confidential information stored within Airflow variables, particularly when these values are structured as JSON objects containing nested secrets. This exposure creates risks for organizations relying on Airflow for workflow automation where variable values may contain production credentials or business-critical data.
Security professionals should recognize this vulnerability as a variant of CWE-20 Improper Input Validation combined with CWE-521 Weak Password Requirements, though the specific manifestation occurs within template rendering contexts rather than traditional input processing. The issue aligns with ATT&CK technique T1552.001 Unsecured Credentials and T1078 Valid Accounts, as it exploits legitimate user access permissions to extract sensitive data from system components that should maintain confidentiality. Organizations implementing Airflow for workflow automation must consider this vulnerability as part of their broader security posture assessment.
The recommended mitigation strategy involves upgrading to Apache Airflow version 3.3.1 or later, where the masking logic has been enhanced to properly handle nested variable values regardless of their data type. This upgrade resolves the isinstance(str) guard failure by implementing comprehensive type checking that ensures all sensitive variable content undergoes appropriate masking regardless of whether it is stored as a simple string, dictionary, or other complex data structures. System administrators should also implement additional monitoring for access patterns to rendered templates and consider restricting access to these interfaces where possible to minimize potential exposure windows.