CVE-2026-68968 in Airflow
Summary
by MITRE • 08/12/2026
Apache Airflow's Backfill API authorized a request against a Dag id supplied by the caller whenever the `backfill_id` path segment failed to parse. The authorization dependency parsed it with `int()` while the route handler parsed it as pydantic's `NonNegativeInt`, which accepts values `int()` rejects (`1.0` coerces to `1`); FastAPI resolves dependencies before endpoint validation, so the two acted on different Dags. An authenticated user holding edit permission on any single Dag could therefore read, pause and cancel backfills belonging to any other Dag, including moving another Dag's queued runs to `failed`. No non-default configuration is required and backfill ids are sequential, so finding a target is trivial. Users are advised to upgrade to apache-airflow 3.3.1 or later, which parses the backfill id with the same type the routes declare.
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability in Apache Airflow's Backfill API represents a critical authorization bypass that stems from a fundamental mismatch in data type parsing between dependency injection and route validation mechanisms. This issue arises from the inconsistent handling of the `backfill_id` parameter where the authorization layer parses this value using Python's built-in `int()` function while the route handler utilizes pydantic's `NonNegativeInt` validator. The discrepancy occurs because `int()` strictly requires integer input whereas `NonNegativeInt` accepts numeric values that can be coerced to integers including float representations like `1.0` which successfully converts to `1` but fails when passed to `int()`. This fundamental parsing difference creates a security loophole where authenticated users with edit permissions on any single DAG can exploit the inconsistency to gain unauthorized access to backfill operations belonging to other DAGs.
The operational impact of this vulnerability extends far beyond simple information disclosure, encompassing complete control over arbitrary DAG backfill operations within the system. An attacker with minimal privileges can leverage this flaw to manipulate queued runs across different DAGs, moving them from queued states to failed status which effectively disrupts workflow execution and creates cascading failures throughout the automated pipeline infrastructure. The authorization bypass enables users to read, pause, and cancel backfills belonging to any other DAG in the system, fundamentally undermining the integrity of the access control model that Airflow implements. This capability particularly affects organizations relying on Airflow for mission-critical workflows where unauthorized manipulation of backfill operations could result in significant operational disruptions and data inconsistencies.
The vulnerability's exploitation is remarkably straightforward due to the sequential nature of backfill IDs and the absence of any non-default configuration requirements. Attackers can systematically enumerate valid backfill IDs to identify target operations, making this a particularly dangerous flaw that requires minimal effort to exploit. The fact that no special configuration is needed means that organizations using default Airflow installations are immediately at risk, regardless of their security posture or network segmentation measures. This vulnerability aligns with CWE-284 (Improper Access Control) and represents a classic case of authorization bypass through inconsistent validation mechanisms. From an ATT&CK perspective, this flaw maps to privilege escalation techniques that exploit inconsistencies in access control implementations.
The recommended mitigation involves upgrading to Apache Airflow version 3.3.1 or later where the parsing mechanism for backfill IDs has been unified to ensure consistent type handling between dependency injection and route validation processes. This resolution addresses the root cause by ensuring that both authorization layers and route handlers process the `backfill_id` parameter using identical parsing logic, thereby eliminating the window of opportunity for exploitation. Organizations should also implement immediate monitoring for unauthorized access attempts and consider implementing additional access controls or network segmentation as defensive measures while awaiting the upgrade process. The fix demonstrates Apache Airflow's commitment to addressing security vulnerabilities through comprehensive code review and consistent validation practices that align with industry standards for secure software development lifecycle implementation.