CVE-2026-25604 is a security vulnerability identified in the AWS Auth Manager component of the Apache Airflow Providers Amazon package. The root cause is an origin validation error (CWE-346) where the system accepts the origin of a SAML authentication response as provided by the client without verifying it against the actual instance URL. This improper validation allows an attacker to reuse a valid SAML response issued for one Airflow instance to authenticate against other Airflow instances, potentially bypassing access controls and gaining unauthorized access. The vulnerability affects version 8.0.0 of the provider and was publicly disclosed in March 2026. The flaw undermines the trust boundary of SAML authentication by failing to confirm that the authentication response corresponds to the intended Airflow instance. This can lead to unauthorized access across multiple Airflow deployments, which may have different roles and permissions configured. Although no known exploits have been reported in the wild, the vulnerability presents a significant risk due to the nature of SAML authentication and the critical role Airflow plays in orchestrating workflows and data pipelines. The recommended remediation is to upgrade to version 9.22.0 or later, where proper origin validation has been implemented to ensure the SAML response origin matches the instance URL. This fix prevents the reuse of SAML tokens across different Airflow instances, restoring the integrity of the authentication process.

The impact of CVE-2026-25604 is primarily on the confidentiality and integrity of Apache Airflow deployments using AWS Auth Manager for SAML authentication. By exploiting this vulnerability, an attacker can gain unauthorized access to multiple Airflow instances by reusing valid SAML tokens issued for other instances. This cross-instance token reuse can lead to unauthorized data access, manipulation of workflows, and potential disruption of critical data processing pipelines. Organizations relying on Airflow for orchestrating sensitive or business-critical workflows may face data breaches, unauthorized privilege escalation, and operational disruptions. The vulnerability undermines the isolation between Airflow instances, which is especially concerning in multi-tenant environments or organizations with segmented Airflow deployments. Although availability is less directly impacted, unauthorized access could lead to malicious modifications or deletions of workflows, indirectly affecting service availability. The ease of exploitation without requiring user interaction or additional authentication makes this vulnerability particularly dangerous. The lack of known exploits in the wild suggests it is either newly discovered or under limited active exploitation, but the risk remains high due to the critical nature of the affected component.

To mitigate CVE-2026-25604, organizations should immediately upgrade the Apache Airflow Providers Amazon package to version 9.22.0 or later, where the origin validation flaw has been corrected. Beyond patching, organizations should audit their Airflow deployments to identify any unauthorized access or suspicious authentication activity that may have occurred prior to patching. Implement strict network segmentation and access controls to limit exposure of Airflow instances, especially in multi-tenant or multi-instance environments. Review and tighten SAML authentication configurations, ensuring that identity providers and service providers enforce strict origin and audience validation. Employ monitoring and alerting on authentication anomalies and cross-instance access attempts. Consider additional compensating controls such as multi-factor authentication (MFA) for Airflow access and regular security reviews of workflow permissions. Finally, maintain an up-to-date inventory of Airflow instances and their authentication configurations to facilitate rapid response to any future vulnerabilities.