CVE-2026-94135 in Airflow SFTP Provider
Summary
by MITRE • 10/16/2026
The Apache Airflow SFTP provider's deferrable code paths (`SFTPTrigger`, `SFTPHookAsync`, `SFTPClientPool`) disable SSH host-key verification by default unless the connection explicitly sets `no_host_key_check` to false. Deployments that run SFTP sensors or operators in deferrable mode are affected. An attacker in a machine-in-the-middle position between the triggerer and the SFTP server can impersonate the server and capture the credentials or data exchanged.
Users of apache-airflow-providers-sftp are recommended to upgrade to apache-airflow-providers-sftp 7.0.0 or later. This is a separate defect from CVE-2026-94134 (the synchronous SSH hook default, which also affects the SFTP hook); users who applied the fix for one also need this release for the other - apache-airflow-providers-sftp 7.0.0 fixes both.
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Analysis
by VulDB Data Team • 10/16/2026
The Apache Airflow SFTP provider contains a critical security vulnerability within its deferrable code paths, specifically affecting components such as SFTPTrigger, SFTPHookAsync, and SFTPClientPool. This flaw manifests by disabling SSH host-key verification by default unless the connection configuration explicitly sets no_host_key_check to false. In standard Secure Shell (SSH) protocols, host-key verification is a fundamental mechanism used to ensure that clients are connecting to the intended server rather than an imposter. By omitting this check in asynchronous execution modes, the software fails to validate the identity of the remote SFTP server against known public keys or certificate authorities. This design oversight creates a significant gap in authentication integrity for workflows utilizing deferrable operators and sensors, which rely on these specific async hooks to manage long-running tasks efficiently without blocking worker slots.
The operational impact of this vulnerability is severe, as it exposes deployments running SFTP operations in deferrable mode to man-in-the-middle attacks. An attacker positioned between the Airflow triggerer or scheduler and the target SFTP server can intercept network traffic and impersonate the legitimate server. Because host-key verification is disabled by default, the client will accept any presented SSH key without raising an alert regarding a potential identity mismatch. This allows the adversary to establish a fraudulent connection that appears valid to the Apache Airflow instance. Consequently, sensitive credentials such as usernames and passwords transmitted during authentication can be captured in plaintext or intercepted before encryption fully secures the session data. Furthermore, any files uploaded or downloaded through these compromised sessions are at risk of being exfiltrated, altered, or replaced with malicious content without detection by the orchestration platform.
This vulnerability aligns with CWE-295 Improper Certificate Validation and CWE-384 Session Fixation concepts within the broader context of insecure cryptographic practices. It also maps to MITRE ATT&CK techniques related to Man-in-the-Middle attacks, specifically those involving credential interception or protocol manipulation where trust is established without proper verification of server identity. The lack of default host-key checking violates best practices for secure remote access protocols and undermines the principle of least privilege by granting unauthorized entities potential access to internal data stores via compromised SFTP channels. Organizations relying on Apache Airflow for ETL processes, log aggregation, or sensitive file transfers must recognize that deferrable modes are not exempt from these foundational security requirements despite their performance benefits.
To mitigate this risk, users of apache-airflow-providers-sftp are strongly advised to upgrade immediately to version 7.0.0 or later. This release addresses the defect in both synchronous and asynchronous SSH hooks, ensuring consistent secure behavior across all execution modes. It is important to note that this issue is distinct from CVE-2026-94134, which pertains to the default settings of the synchronous SSH hook. While applying a fix for one vulnerability may improve overall security posture, it does not resolve the specific flaw in the deferrable code paths addressed by version 7.0.0. Therefore, organizations must ensure they have applied this specific update to fully close the gap that allows host-key verification bypasses. Until upgraded, administrators should manually configure all SFTP connections used with deferrable operators to explicitly set no_host_key_check to false and implement additional network-level controls such as IP whitelisting or mutual TLS where feasible to reduce exposure to interception attacks.