Airflow SSH Provider EUVD-2026-102521

Exploitation requires BOTH: (1) an affected deployment using apache-airflow-providers-ssh or apache-airflow-providers-sftp before 7.0.0 with an SSH/SFTP connection that relies on the vulnerable default - i.e. host_key is not configured AND no_host_key_check is not explicitly set to false, so unknown server keys are silently accepted; and (2) the attacker occupying an active machine-in-the-middle position on the network path between the Airflow worker and the SSH/SFTP server to present a forged host key. Limiting factors that reduce realistic risk: the MITM foothold is a non-trivial network prerequisite (no remote-from-anywhere exploitation); deployments that already pin host_key, maintain known_hosts entries, or set no_host_key_check=false are not affected; and upgrading to provider 7.0.0 (which changes the default to secure) fully remediates. No user interaction or authentication to Airflow is needed by the attacker.

The input assigns CVSS 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N), which rates this Critical, but multiple independent signals argue the real-world urgency is materially lower than that number suggests. The decisive caveat is attack complexity: exploitation requires the attacker to already hold a machine-in-the-middle position on the network path between the Airflow worker and the SSH/SFTP server. That is a precondition outside the attacker's control, so the vendor's AC:L rating is questionable - a defensible assessment is AC:H, which drops the base score to roughly 7.4. The remaining signals reinforce a lower priority: EPSS is only 0.18% (7th percentile), there is no CISA KEV listing (not actively exploited), and no public exploit code was identified. Availability impact is correctly N; the harm is confidentiality and integrity of intercepted credentials/data. Net: this is a genuine design weakness (insecure default) worth patching on a normal maintenance cadence, but it is NOT a drop-everything emergency - it is a high-CVSS, lower-real-risk issue gated behind a significant network-position prerequisite. Note the signal tension explicitly: CVSS AC:L implies easy exploitation, yet the description's requirement for an active MITM foothold implies conditions beyond attacker control - verify complexity against your network trust model.

An Airflow deployment runs SSH/SFTP tasks using a connection that relies on the default (no host_key set, no_host_key_check not explicitly false). An attacker who can intercept or redirect traffic between the worker and the target server - e.g. via ARP spoofing, rogue DHCP/DNS, or a compromised network segment - stands up a server presenting a forged host key. Because host-key verification is disabled by default, the worker accepts the impersonator and transmits the SSH/SFTP credentials and task payload to the attacker. No public exploit code was identified at time of analysis.